Here's a random idea.
Assuming ur mac mini is defo not going anywhere....it's a full time desktop system.
Say like me your not bothered about the working functional part of the pc not being aesthetically pleasing (my pc is tucked away out of sight....just the monitor etc on my desk so it's neat and tidy)
Will the mac mini boot without its case on? Then bolt on a beefy cooler or aio cooler to it? Obviously ud need to leave the fan plugged in but if it's in a cupboard or something anyway you'd not hear it and it would run on its lowest rpm anyway .... And just run any cooling fans off USB adapters - again id have a plethora of dongles and adaptors turning the 4 usbc ports into tens of USB 3....display ports and what not.....again all hidden away so you'd not see or know.
You'd end up with a clean functional design and desk, running a proper mac mini who's maxed out load temps would probably be 60c or less.....and easy access to wack in 64gb ram!
Sort yourself a egpu and I reckon it would be a fairly beastly system that wouldn't throttle and end up Out performing an imac pro, in most editing bits n bobs....not export obviously but it would be way more silent than a fully maxed imac pro at 100% cpu.
I'd also consider putting the parts in an empty classic mac pro tower if I wanted a clean look......literally bolt the mini in there and keep all the dongles in there also and just have clean cables coming out the back.....that would be a sweet mod but using genuine apple parts.....wonder if the egpu would also be able to fit in....fun idea here.