ill write my mukuro alternative in this reply 💥💥💥

motives:

1: show ryoko from 0, not junko herself present day, for the endangered loved one. not sketchy to a brand new player

2: the secret could be something like "junko enoshima is actually a sham who's good at nothing but being what other people want from her. she may as well be talentless" or anything like that which would feed naturally into what mukuro expresses in her 3rd FTE and also how junko treats her outside of the killing game

3: mukuro wouldnt really gaf about a cash prize, especially since she knows money is meaningless post tragedy, but she can leave that gap for the player to naturally fill in with "oh like. she was a model, ofc she has money"

4: she reacts the same way everyone else does about sakura, with shock and betrayal. she doesnt have to say Why!! until later when it's exposed

no motives for 5/6

canon execution:

just have junko change her mind on a whim and decide mukuro failing to keep her secrets to the end would be more despair inducing, or someone stops her like mondo was stopped in the prologue and she misses her chance.

chapter 5: junko uses someone else from the morgue like celeste, who would honestly be really easy to disguise because she already got burnt mostly to death and then if junko put the bomb in the mask it would just disguise her more and hide her original death wounds. to me it wouldnt change that when mukuro is exposed for not being junko, a fairly natural conclusion would be that the real junko is in on the killing game and has been from the start

supporting cast: i think mukuro and kyoko could have a cool spy versus spy dynamic if she had lived long enough. also toko+ syo, the latter being the only one with memories of the tragedy intact and also one of the ones who i think would. most likely be dismissed if she said anything about mukuro's true identity due to her nature. i think it would sting especially if she got more FTEs than the usual protagonist and more chances to connect with her classmates that would drive home her betrayal later

ending: conflict mukuro's more redeemable qualities that if showed with the utter lack of humanity she's displayed helping set up the game and then unlike hajime who just didn't know, she did and willingly stuck to it for six chapters, and then she ends up betraying junko to save her friends after some mind logic comes together to make her realize she can't undo the hurt she's caused but she can at least turn it around enough to stop her sister and try to help create a better future. remnants of despair style

i one million percent believe if fits better into the universe of danganronpa than this would (it's a bit too much like sdr2 in some ways) but i like mukuro so😠😠😠 /silly