Check out Pipewire, which is the modern standard of linux audio
I do not have the same requirements than you, but in audio production I can route anything in any which way I need (useful for switching monitoring or sources), and I did once plug an eq to my movie player because some ripped movie was really sounding bad
There are tons of VSTs available, too
There’ll be research to do, and a learning curve, but today is not the days of Jack anymore, it has become really easy if you go for a modern distro (arch, tumbleweed, fedora,…)