What is the advantage of bionics over flesh?
Quick and easy repair, no pain or bleeding, excellent performance, although of course very expensive.
So why can we only replace arms legs and some silly organs?
There's a similar problem in RimWorld.
You can do extreme cybernetic modifications, completely replace all organs and limbs of your colonist, even the brain (with mods), but you can't replace his torso, neck or head. As a result, this “superhuman” dies from one good hit to one of the above mentioned body parts.
This problem is not even solved by mods.
A bit far off topic, but I think it's important to understand the point.

What do I propose to add?
Cyberaugmented skeleton, skull, spine, circulatory system and muscular system with obvious bonuses over the usual ones and standing in the second tier together with cyberaugmented organs.
How is all this ♥♥♥♥ going to be installed? Standard tools are obviously not going to be enough, are they?
The next item can be realized as an improvement for the medical bed.
A surgical bench with auxiliary manipulators and a life support system. It will consume a lot of electricity and will be very expensive. For any person lying on a bed with it, it will give a bonus +50 to all skills for medicines or anything else applied to them.
Also, for severely injured patients or advanced operations to replace/improve important body parts, there will be an option to plug it into the poor bastard with a special item that will need to be disconnected before letting him go about his business to avoid irreversible consequences.
Once connected, it will replace the functionality of all vital organs and allow the user to live without most of their body, consuming neutroamine in return.
It will also give effects similar to a stasis bag.

Fully cybernetic implants of head (along with neck), torso, arms and legs (which will be further referred to simply as bionics) will be divided into 6 tiers with increasing cost and difficulty of obtaining them. Each tier will have its own pros and cons and it will make sense to use less technologically advanced bionics. There will also be a system of modules that improve functionality and characteristics with a similar division into tiers. These will include built-in weapons, tools, various systems and additional organs.
Simple Bionics(1) - Legs and arms only. 25% less effective than normal human limbs. Very cheap to craft, but requires uranium and lead for insulation. Breaks down very quickly in water. Can zap the wearer with an electric shock when taking significant damage. In a worst-case scenario, it can explode with minor force, irradiating everyone in a small radius. Not upgradable. There will also be a pirate uncraftable version with 100% effectiveness, more durable, but with a very small chance of jamming at the worst possible moment.

Standard Bionics(2) - Will match the cybernetic limbs already available. Will be in regular and waterproof versions. The non-waterproof version of the torso and head will exist more as a joke/challenge. Very flexible and allows the installation of plenty of modifications including artificial skin.

Military Bionics(3) - A military modification of the 2nd tier. Will have armor that protects mechanisms from all damage and the wearer from pressure at a depth of 4000 thousand meters, but loses durability for repair requiring Titanium-Aluminum Alloys and no pressure. Will be 50% better protection against EMP. When fully the same tier and with functional modified thorium rod with reinforced shielding will give strength comparable to an exosuit. Does not improve any skills other than weapons, does not speed up movement, and holds fewer modifications. Cannot be modified with artificial skin.

Advanced Bionics(4) - Recent advances in biomimetics, the use of advanced materials and living metal have allowed these bionics to slowly regenerate damage plus they are resistant to EMP, though it shuts down regeneration for a modest amount of time. These implants look exactly like living ones and cause almost no cyber-psychosis! There is also a line of organ and brain implants that negate the risk of cyberpsychosis, but can only be used within the T4 ecosystem. That's where the pros end. These bionics do not have any moddability other than installing additional organs. Cannot be repaired like other bionics, but basic regeneration can be accelerated by injection of nanomachines. Serious damage can be done to the artificial skeleton, which takes much longer to regenerate than the outer layers, and in addition, if 100% damaged, the limb cannot be repaired and loses functionality permanently. Such damage to the head will quickly cause brain damage and kill the person, the chest may not kill immediately, but it will cause serious complications. Also requires twice the amount of neutroamine to maintain.

Experimental Bionics(5) - Insane price, requires the best minds to produce, expensive to repair and maintain, yet opens new horizons for mankind. Pure performance, durability, strength comparable only to the fearsome predators of europe. Its own line of organs, though these are more like high performance and robust life support systems for what's left of the average human. Huge potential for modifications and their number inaccessible to more primitive models will allow to adjust this system to any requirements and tasks. Who needs quantum computers in the brain if you can replace all organic matter with advanced nanomachines? Despite all the advantages over the lower generations, modification of this bionics should be carried out wisely in order not to complicate the already galactic scale war with psychosis and not only...

Elite/Legendary Bionics(6) - Can't be made, bought with money, or just found on a simple rusty wreck. It can be almost anything, but it's bound to be something very unusual and difficult to obtain. Alien technology? An arm with an experimental plasma cannon? Faction-specific stuff, or Easter eggs? That's where my imagination ends.

A specialized fabricator will be used to produce cybernetic parts above tier 1. New materials should be introduced. Separate add-ons for integration with other modifications are possible for modules.
The above is only my idea of ​​how the finished mod should look, in no way a requirement. From all this, it would be good to release at least the torso and head of tier 2, then the mod would become much more interesting.

assisted by stupid-ass online translator