And ship a commonjs version as well, if you need to support older node versions. It's trivial.
I assume that you're talking about tools rather than libraries. Any simple library can import ESM asynchronously and any ESM packages can import CJS packages even with static imports.
Tools and Node’s strict ERR_REQUIRE_ESM have been the problem with the migration.
Just save yourself some headache and publish either ESM or CJS, not both.