Okay this is probably not going to be the answer you want but…
Keep him!
You’ve always been the main care giver and it sounds like you love him.
You clearly only want the best for him and that is why you’re reluctant to let anyone else have him.
You didn’t choose him, but he chose you, and you go and forage for the good stuff on his behalf every morning, bathe him etc. Sounds like love to me.
So maybe just keep him and find a good pet sitter for when you’re away.
Also, don’t let your daughter have him back! She can babysit occasionally if she is worthy.
Sorry, I might be a little bit biased as grew up with tortoises and had very minimal responsibility (thanks Mum!)
Anyway, if you can’t keep him I’m sure there must be somewhere that would take him on.
But don’t you think you’d miss him?