From my experience having attempted to migrate away from VSCodium (in the attempts to de-VSCode) and build atop Theia as a platform, there are few things to consider:

- The build system is finicky and can easily take hours to figure/fix.

- The error-reporting is severely lacking. You can be lost why something internal isn't working and go on a rabbit-trail with your favorite AI-copilot, etc.

- Documentation is lacking. You have to dive into the platform code to actually figure things out.

- This can be seen positively but there are quite a few new things being introduced regularly (especially AI-related) which, for a platform, isn't always ideal.