Also to destroy your point on Rust making it safe for your end users.

Library that doesn’t have stable C API is next to useless outside of its original language/community/etc. and I have been bitten by this a few times already myself (my great libraries in D’s std cannot be easily exported outside of D).

Do not repeat my mistakes - provide stable C API (and ABI by extension) as soon as you can. You cannot make it safe though it’s simply not accounted for in the land of linker “technology”.