> I've never set up a highly available Postgres and Redis cluster on dedicated hardware, but I can not imagine it's easier than doing it in AWS which is only a few clicks and I don't have to worry about OS upgrades and patches

Last I checked, stack overflow and all of the stack exchange sites are hosted on a single server. The people who actually need to handle more traffic than that are in the 0.1% category, so I question your implicit assumption that you actually need a Postgres and Redis cluster, or that this represents any kind of typical need.