I really don't get it how anyone can still tolerate the shitty software upscaler on base console or the shitty IQ in more demanding games but ok.
it's funny that you say this and the first solution the comes to mind is an overpriced as fuck piece of hardware with a walled garden, IF you really cared that much about IQ the only option would be to buy a PC, infinitely more customization where you can choose where to spend your resources to get the IQ you like the most.
Honestly, PS5 Pro offers so little improvement that it is not worth it at all (right now), specially if you take into account that most games (some of the best available, also) are on PS4.