When I'm writing some frontend that is hosted on localhost, with an API that is hosted on its domain somewhere, it always is some sort of PITA to get the dev environ started.
There's a plugin for firefox that ignores CORS which is helpful for this. It's becoming less useful for me as my APIs now usually have a toggle to add a cross origin header which allows localhost. Still useful.
Integrates nicely with existing JS frontend tooling.
I assume this would also work for CORS purposes: for some time I've not used localhost where possible, for SSL reasons. Giving the local machine a perfectly valid name that I can get a cert for via LE (or already have a cert for, I actually use a non-production name for which I maintain a wildcard cert) is slightly less faf than having my own signing cert installed as trusted everywhere I might need it. Anything I might do publicly is HTTPS-only so my dev/test environments are too.