If I return a customized solution (C ++ service "compiled with g ++ and gcc", API in PHP and Angular interface, PostgreSQL database) and create a customized ISO with Debian to distribute my software. Will my solution become GPL and will I have to open the source code? or I can continue with the closed code "proprietary", today due to this doubt I FreeBSD, but I would like to use Debian, because I find it easier and more stable.
Today I am careful when using libs. I use MIT, BSD licenses or in the worst case LGPL, depending on the need I write a new library, just to not have license problems.