You might be able to find a compromise in M-ATX form factor.
Smaller than normal ATX, but less of a price premium than ITX, easier to find ... spatially compatible higher end GPUs, and people do make more compact M-ATX cases.
https://www.gamingpcbuilder.com/motherboard-size-guide-e-atx-atx-matx-itx/

EATX, ATX, MATX, ITX.
Now your taste in cases may be different than mine, and I've no idea what EU prices look like, but...
Asus Prime AP201

Jonsbo D30

ThermalTake Tower 300

... if you want to be a bit of a show off, haha.