I use Inoreader as my RSS backend, they have that feature. They provide an email address, and everything that lands in that inbox pops up in my RSS feed. So I have a rule in my email inbox which forwards all their emails to the Inoreader address

TSG doesn’t really support integrations like that. There are unofficial workarounds, but they’re prone to break. Adding an API is on their roadmap, but might be a long time in the future

There’s also https://github.com/awesome-selfhosted/awesome-selfhosted