I did a huge chunk of work to split deno_core from deno a few years back and TBH I don't blame you from moving to raw rusty_v8. There was a _lot_ of legacy code in deno_core that was challenging to remove because touching a lot of the code would break random downstream tests in deno constantly.
Thanks for that work! deno_core is a beautiful piece of work and is still an option for OpenWorkers: https://github.com/openworkers/openworkers-runtime-deno