Check out using ddns. It’s not perfect, but works. There are updater containers you can run. NoIP used to have freebie domains, I bought a domain a while back, then switched to cloudflare for convenience despite it being cloudflare (you can leave tell them not to use their proxy for individual sub-domains). Bonus points for using something like nginx proxy manager or cert-manager to handle acme LetsEncrypt certs, because unencrypted http is BAD.