I had a chance to use UHD 630 for mild Linux gaming for a couple of months 5 years ago. So far it was good. Was able to Minecraft (No shaders though) with decent fps and a couple of 3d browser games such as Forward Assault (Some Counter strike like game), Tetr.io and Bemuse.
For Steam games… it was able to play 2d games great. Majority of newly released 3d games (Indie, triple A is out of the question) that time, the iGPU struggleds however.
Well I only wanted to play Skyrim at 1080p and it was able to deliver.
Also was able to play Dota and Counter Strike Global Offensive too.
I don’t think the newer intel iGPUs are any better, I mean it can play 3d games fine but usually performs OK on games a generation behind or older.