Welcome @Elpastore !
First, note that it turns out that the original issue had nothing to do with permissions. File names in Linux are case-sensitive, and the issue appears to have been related to that.
Second, changing the UID that nginx runs as is really a bad idea. Should there be any exposed vulnerability to nginx or any of the applications being run within it, or a mis-configuration in a conf file, you’ve now put all files owned by you at risk.
If you’re going to be using and managing a Linux server for your web applications, you want to adapt your processes to how things are intended to be done - and that includes working with the permission system, not looking for ways to work around it.
Yes, there is a lot to learn in that area - and the “best practices” do evolve over time. But satisfying the objectives of a stable, reliable, and secure environment require that effort.