Here's my mod that does this with some buttons:
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=3119663996
The mod just provides buttons to do the same thing you can do with commands. Doesn't matter which one you use.

This command will give characters with skill trees all 15 insight points, mark final bosses as defeated for lunar and shadow affinity, and do Wigfrid's more specific tasks.

PLEASE NOTE! Your current skill trees progress will be erased and overwritten!

Open the console by pressing "~". This button is usually below "Esc" and left of "1".
Paste this into the console and press enter:
Your game may freeze for a bit while it's pasting.
You must use this command from the main menu.

Here is a human readable version of the code above:
You cannot paste this into the game, as it has multiple lines.

An alternative way to write this without loops and variables would look like this:

Manually change XP:

To modify other characters, replace wilson in the code snippet above to one of these:
Note! Wigfrid is referred to as Wathgrithr in the code!

As for the amount, 160 xp is 15 skill points.
Oddly enough, 0-4 xp is 0 points, 5-12 is 1 point, etc. I don't know the pattern.

Alternatively, you can use
This adds XP instead of overwritting it, but otherwise they're the same.




Here is how you can mark bosses as defeated (for lunar and shadow affinity), and complete Wigfrid requirements:
Copy and paste any specific line.

No. This functionality, these commands, were provided by Klei themselves. I just formatted it for easy copy-pasting.

When Klei cares about something, they protect it in the code.
This is why there is no way to play a DLC character you don't own using console commands, or unlock skins.
Skill trees, on the other hand, have no protection at all. Klei doesn't care.