If you can't use a tool like Caddy that manages SSL/TLS certificate renewal, there are a few ways you can monitor your certificates to be alerted when they are close to expiring.
Netlify is a great way to host and deliver static sites, one downside is that by default it only allows you to use GitHub, GitLab, or Bitbucket. It is however possible to automatically deploy your site to Netlify even using a repo hosted with any Gitea instance.
Drone is a CI/CD server that can be extended to handle many different specific use-cases, however the Drone Server communicates with extensions via Webhooks which require you to manage a separate web process for each extension. Merging a drone extension into an OpenFaaS function removes a lot of the maintenance cost of using Drone Extensions.
Drone is a CI/CD server that supports many different forges (GitHub, GitLab, Gitea, and more!) and OpenFaaS is a provider agnostic functions-as-a-service solution. Combining these two takes OpenFaaS to the next level with GitOps. An alternative to this guide is to use OpenFaaS cloud which provides multi-user capabilities and more than this guide can provide, but you are limited to GitHub, and GitLab as git providers.
In case you don't want to share access to your Gitea instance but want to provide access to your code you can mirror your git repos to GitHub