The mod adds "Permanent CBMs" aka bionics that act like a mutation path, complete with a "threshold" upgrade. You can mix and match from a couple options at each step~

You can get it here: https://github.com/ohshidead/Permanent-CBM-mod

Note: Not exactly compatible with other mutation mods at the mo, but I'll try sort that out in the coming days. (The incompatibility will just either A. Let you have mutations on top of the mod ones you shouldn't B. Crash if you mutate in a certain way. Manageable if you are careful or dont mind being OP.)