HopeInShyTown wrote:
Hi, thank you. Although I don't want to go all the way to Ventura do to software compatibility issues. I would like to do Catalina or Big Sur.
Catalina and Big Sur will break 32-bit applications every bit as much as Ventura would. (Catalina is where Apple dropped support for 32-bit applications, and broke up iTunes.)
If you have 32-bit applications that you want to continue to run, you will want to remain on High Sierra or Mojave on at least one of your startup disks.
And, why are they not showing in the app store?
The App Store hides old versions of macOS by default. It will only show them if you go through special links, like the ones in this Support article.
How to download and install macOS - Apple Support