Hi, as g90ak mentioned, he also has adapters for onaholes. The adapter I got is similar to the one on the handy so if you can strap the onahole you have, you should be fine.
One minor issue I have is that soft ona’s will need support if you strap it similar to handy sleeves (the opening flushed with the bottom of the adapter). On fast scripts, the ona will flop around but it’s a minor issue since you can just strap the ona in the middle to keep weight balanced and tweak the starting position for the osr2+.
But I am a slut for slow bj scripts so my needs may differ from yours.