Whether you dev/test on localhost or a remote instance (or a local instance with a public name etc.), is separate from whether your dev/test instances present via HTTPS.

Its a bit easier to use letsencrypt on a remote host. In less than 5 minutes i can setup a remote host with domains and certificates attached to it. Localhost with certs and hostnames is always a pita. Thats why i always work on a remote box. For my local editors it doesnt matter. Just attach remote disks to my local machine.

I think the relevant part here is that remote hosts have public IPs. I'm assuming you're doing HTTP-01 verification on Lets Encrypt, which does basically require a public IP.

FYI, you can get Lets Encrypt certs easily on non-public hosts by using the DNS-01 challenges. They rely on setting particular DNS records rather than HTTP responses, so they don't rely on public IPs