Just tried BleST (3.1.0 master from the GitHub) in Blender 2.90(alpha). I loaded my 2.83 settings on startup to transfer then to 2.90a. Imported a couple of models of various types, Exported and compiled. Things seem to be working ok. Have to test animations yet. but getting models into and exporting from Blender 2.90 seem to be alright using the current master from the GitHub.

I haven't tried the current BleST stable (3.0.3) though.