
I looked for the novel and found it. I just started reading it. Apparently, the ending is vague and seems to suggest a 3p ending.
For anyone interested, here's the novel link: https://littlepinkstarfish.com/the-snake-that-swallowed-the-pomegranate/

Wait, I forgot what Sylvenian did in past life? Like how did he live previously

It was mentioned in the earlier chapters that he was previously tossed aside by Rosie in 3 years after she claimed Mikael. It's likely he suffered some form of negative effects after getting tossed aside post-imprint (eg. depression etc). Or he went back to being a guard but with PTSD from all the SA he received from Rosie. But seeing as how the royal family treats their kind like toys Rosie may have lost him in a bet, had him fight other homoculi as a disposable pawn, or as mentioned by Haru above sent to do labor. It wasn't really elaborated since the focus shifted to Mikael and Rosie but yea. I don't think it he lived well after.
In bonus 9, the author said mullet will become a global trend and it really did...