If you want a full suss then this is a good option. Trek Ex Junior.
https://www.sunsetmtb.co.uk/shop/index.php?product_id=7973
It weighs around 13.5kg if I recall. My eldest did some good stuff on it when he was ten/eleven. Much more capable than his Iskabike Creig, but also much heavier.
If you know the steep climb near the end of Llandegla red route, just past the cave seat. He manages that fine despite the weight. He did the west highland way on it. Though I did carry it up all the big hills for him, which was tiring.
His wee brother has it now and loves jumping it. Send to cope well enough.
Also as someone above mentioned, Commenced do s cracking 24″ full suss. We hired one in Tignes 2 years ago and it was amazing for lift served stuff.