So, as the title says - can body MODs be forcefully installed through any kind of events? Like if Lona is captured and sold, can she be forced to undergo operations or receive these MOD conditions through any other ways? 

I am curious if the clinic is, in fact, the only way.

Nop, so far it seems that only elise can do it due to his very unethical practices, But you should go ahead and suggest it in the discord!
i honestly would love to see underground doctors who are equally or more psychopaths than elise, lol.

Well, that's a shame. But hey, would love to see it in some form in the future )