Yes, this is indeed a common technique we have always had in mind - exactly for the reasons you stated. It’s also what the folks at Microsoft that work on our official Archetypes and Maven plugins advised in addition to using Velocity and Groovy.
I will try to do what makes the best sense to me and we can review the PR together to see what could be improved. Similarly we should continuously think about evolving the code together as we add more features.
I am very hopeful a sensible evolutionary path will be pretty obvious and should not require much contention.
I'd like to point out that there's one solution for the archetype to keep the code for each Jakarta EE version separate and still release everything as a single archetype.
The archetype can have multiple code templates in different folders, one folder for EE 8/9 (with only javax/jakarta change), one for EE 10, and separate ones for any future version. Everything can be then filtered in the groovy script that runs after the project is generated. The script could easily delete directories not related to the chosen EE version. I know, it's a bit awkward that it would first copy files for all EE versions and then delete all versions but one, that's a limitation of the Maven archetype plugin, but I think it would work pretty well.
Ondro