AMD Ryzen systems will work with any version of macOS from High Sierra to the latest Ventura release. Your Asus B550 system with a 6-core CPU is nothing out of the ordinary.
See the Ryzen guide below.
Only issue I see with your setup is the Legacy AMD HD 5870 dGPU, which would restrict the system to running High Sierra.
If you can get hold of a Polaris, Vega or Navi AMD GPU then you would be able to run latest release of Ventura.
You can also use an old Nvidia Kepler GPU to run High Sierra up to latest release of Big Sur.