EndeavourOS is basically Arch with a nice installer and a few extra QoL packages while Manjaro manages their own repositories and adds things like mhwd that change system management to be a little different than Arch.
I much prefer Endeavour since I already do everything from the command line anyway. Also, while most info about Arch applies to Manjaro it doesn’t always and I found that very annoying when trying to troubleshoot.
I’ve also installed Arch a few times and it went fine, but the Endeavour installer is a much nicer experience.
You will find it very difficult to get help with game piracy on linux just because the community is very small. If the game has a native release it will be even harder since most linux users want to support developers that do native releases. I’ve only ever tried a couple games that I had no problems with and that was a few years ago. These days if it has a native release I will always just buy it.