Have you considered Cloudflare R2? It seems like that's one of the very few unmetered-bandwidth file hosting providers?

It doesn't do HLS out of the box (it's just S3-compatible storage, unlike the pricier Cloudflare Stream). But you should be able to do the transcoding yourself: https://github.com/wesbos/R2-video-streaming

Or what are some other good options for Vimeo replacements?

Or consider Tigris object storage service.