Unfortunately I cannot confirm or deny anything - I can just assume:
You might be able to reinstall the original firmware, but enabling MaskROM probably sets a flag for the iHost and it won’'t be elligible for future updates. At least that is what happens with the NSPanel Pro. You can enable adb and then sideload Android apps.
Afterwards you can no longer receive OTA updates. (However, you could install releases manually, if you can get hold of them).