I wish there was non custodial prediction market on Bitcoin. In the meantime I think the best alternative is Polymarket ( https://polymarket.com )

It is using usdc on polygon which is some Ethereum layer 2 or whatever. They claim it is non custodial and user has private key in the browser and can export it. No need to use metamask or any desktop software. So the only trusted part is switching from Bitcoin to poly usdc that has to go through something like sideshift or similar where they have custody during the exchange.