Toddler taking diaper off at night

I’m at my wits end with this. My 2.5 yo boy will NOT keep his diaper on at night and wakes up soaking every morning.

Please understand he’s doing all of this THROUGH his jammies so the usual putting them on backwards, etc won’t work. He’s also not ready to potty train. I thought this was a sign of that but he literally cries when I put him on the potty.

I’ve tried layering onesies underneath and on top of his footed jammies and he just works around them.

If anyone has any suggestions, I’d love to hear them!