If all else fails, search safe bedsharing
I swallow my baby who's 8 weeks on and I hold him really tight. And then I slowly leave him down as he still sleep. And with that warmth of it being him, he usually stays asleep when I put him down after eating.
It sounds so weird, but get a tall sock and fill it with rice and put it on baby’s belly. You can also try warming up the bassinet or bed with a heating pad first. The sock mimics the pressure of being held. The warmth of the heating pad makes the transition of your body heat to bed easier.
I found this article to be helpful and I do this w my 6 week old and it actually is working https://www.babysleepdr.com/blog/Why-is-My-Baby-Waking-Up-as-Soon-as-I-Lay-Them-Down