Oly

After watching loads of videos on YouTube, my 7 year old daughter (though she's size of a 9 year old) wants to try trials. Had a look on Tarty bikes and seen the Inspired Flow 22 and Jitsie Varial 970... But they're expensive as a give it a go bike (happy to splash the cash if she takes to it) and there doesn't seem to be many/any kids kids trials bikes 2nd hand. But there are alot of 20" Onzas available. How would a "normal" 20" bike compare to the kids version in terms of geometry/length etc. Happy to swap components to customise fit if needed. Cheers folks