As you already may know, the game forces you to choose one colleague (Karl/Mia) to join an afterwork activity with exclusive achievements for every one of them, meaning for a 100% completion you normally need to beat this game two times picking different choices for each playthrough. But worry not, I have got my own saves backed up.

drive google.com/file/d/1XJaPgoNqJ5GTZAk84MRAp-xh_lSHkoPl/view?usp=sharing

Download, extract the above file and run the .reg file you need. Doing so will overwrite your save, so back your own save before if you need it afterwards. And yes, this game's one of those games that saves its config/save data to your OS's registry, the path is:
HKEY_CURRENT_USER\SOFTWARE\Buntspecht Film und Digitales GmbH\FallOfPorcupine.
There are five files in the archive;

Executing act1bargame.reg and completing a minigame and dialogues should grant you:


Drinks and Games
Play the bar game.

act1basketball.reg:


Pump up the Jam!
Play Basketball with Mia.

act2cooking.reg:


Cooking Mia!
Cook dinner with Mia.

act2dumpsterdiving.reg:


Take it from the rich
Give Away the Stolen Groceries

act3phonecall.reg:
I couldn't make two different saves for this one. Decide to call Mia and do her quest upon loading the save for:


All the World's a Stage
Rehearse with the Theater Troupe

Decide to call Karl and do his quest for:


Snowball Armageddon
Have a snowball fight with Karl.