For robot/synth playthroughs:
What if instead of drinking water, the Sole Survivor had to drink Nuka-Colas (classic, cherry, quantum or any variants from Nuka World) in order to sustain his/her "energy" needs (think of Bender from Futurama... In fact the same could apply for alcohol consumables).
Also robot repair kits would replace stimpaks for self healing and for immersion's sake, the model of the stimpak in the self-injection animation could be replaced with a robot repair kit. complete with sound and possibly the shock effect displayed when using one on a robot companion. I assume this last part is quite complex when tweaking game files, especially locating the model, animation and effect files.
Now, I'm an apprentice at modding. I have not yet created a mod myself, but I can't say no to trying my hand at it if someone is kind enough to point me in the right direction.
In any case, thanks for reading my idea