I agree that this could be good to address, but not sure if it is a Bug Report since the lack of functionality has been accepted by staff, so this Bug Report may be closed.
Note that staff didn’t say Windows doesn’t handle HEIC but that
There’s an existing post on workarounds here
https://forum.inaturalist.org/t/work-around-for-heic-photos-on-windows-10-11/75321