That depends on the license. Music is also available on Youtube without authentication requirements but I don’t think you can just download those and do whatever you want with them.

Everything Herb Sutter says about the popularity of C++ should be taken with a huge grain of salt.

Just self host an open source runner like woodpecker and you’ll never have to move again

How painful is the setup and general maintenance/security?

I’m considering the idea but I just don’t want to deal with people abusing exploits in the actions that give them access to my LAN.