News about the topic.
I bought Mac mini i7/512gb/16gb ram +sonnet egpu+Radeon nitro rx580 8gb ram+ Logitech stream webcam (its good for FaceTime) +Asus xonar U7 mkii external audio. I loosen 130gb for boot camp with windows but i have some apps (Proshow and pubblisher) that works only with this OS .
I spent 2500€ but now I am happy because i can change video card, monitor (At moment is a dell 27” 2560x1440 , not 5k but good for my work) or audio card if i have some problem or i want an upgrade.
With 3077€ i can buy an IMac 27” with 512 gb ssd, i7 quad and 16gb ram (video card i see is the same), keyboard and mouse/trakpad but i need go to Apple store (i need 2 hours for go into Apple store) for every problem and I never upgrade iMac .
I am happy for this machine, fast, compact and silence (My box with hdd is more noisily).
I can buy a new pc desktop at half prices (1100-1200€) but i will have same bench for more space and fan noise. Nuc and other systems are similar to mini but i read they work a little bad with egpus.
I wish my Mac mini will work for a lot of years. Thx all for tips and helps.