I've actually never heard of OSR until this moment. I apologize that it more than likely won't function for OSR by the sound of things, however I do have plans in the future for a revamp of the system which acts as its own game disconnected from 5e. For the time being that is mainly an experiment, so Svellera has no current plans to move out of 5e.
You are welcome to join the devlog server to get in contact, however. I'll be interested to see what there is to offer.