Husband is strongly hinting at butt stuff, not sure what to do

Just need some advice if anyone has any. About a year ago when my husband and I were having sex I grabbed his butt a little too close to his *ahem* hole....and I apologized but he actually said he kind of liked it?

I'm totally fine with this, in fact it kind of turns me on tbh. Well I had a mini vibrator and one night I tried putting that down there on him per his request and he seemed to really enjoy it. He's a little shy about admitting how much he likes it and doesn't really talk about it if I ask him straight out. But during sex he will guide my hand there constantly and like, try to push my hand up there almost?

I'm not 100% comfortable sticking my fingers up someone's butt, but I'm down for getting him a toy or something we can use. Does anyone have any recommendations? Something small, not super intense, just to ease into it?

Thank you! And please no judgement