LineageOS has no AVB support at all unfortunately and most devices don't allow using verified boot with custom keys anyways. With GrapheneOS they can just add GrapheneOS public keys (https://grapheneos.org/attestation.json).
For LOS Roblox would have to disable hardware attestation completely, which means you can easily just add extra modules such as a setuid binary which makes cheating easy (at least on the client side, you'd have to rely completely on server side anti cheating)