can mac mini handle the load without eGPU?
I have the middle i5 6-core Mini, and using InDesign, Photoshop, Illustrator, Logic, Dorico and other 'pro' apps, I haven't even comes close to maxing it out. I've even had Handbrake running in the background comfortably.
The on-board SSD is crazy fast. I'd get more RAM for it, though. I have 32GB, which again never gets entirely used, even with loads of caching.
Yes, the Intel graphics units may not be as good as dedicated cards, but they're  good enough for most uses, unless you're doing 3D rendering or high-end gaming. Multiple Photoshop effects layers are not a problem.