I have been searching about this process (the technical part about a migration of Open Source 2.3 project to Commerce version), but there is not too much info out there. At same time, the official resource about this seems so basic https://devdocs.magento.com/guides/v2.3/comp-mgr/upgrader/ce-ee-upgrade-start.html (without having yet the Magento Commerce access)
I have read somewhere you cannot use some 3rd party modules in Commerce version... First question would be: is it correct? If so, then I have lot of doubts at this point
This is purely because of code differences (code which exists in Commerce core version, but it doesn't in Open Source version), or is it some kind of legal thing about modules licensing?
Is there any way or tool to test that upgrade process to have a preview about errors we'll face & be able to plan something to fix them?
Any way to know which modules (apart from the Marketplace ones) we'd need to remove / rewrite?
Apart from the code differences, is there any other requirement about coding quality (such as including testing, etc...) to have a module working in Commerce version?