Orion should be able to fully support userscripts, especially since even Safari has them semi-working. For now, most, if not all userscript managers (TamperMonkey, ViolentMonkey, and GreaseMonkey are the ones I've tried) are either completely broken or only semi-working. I think the best way to go about this issue would be to make an inbuilt userscript manager, just like customCSS, but for javascript.