[Lemmi]

Interesting that he uses.some ext service for caching the images.

Doesn't this creates a security issue with ext content?

Shouldn't this easy to Selfhost through some nginx config?

Like nginx do a proxy pass upstream and cache and return a cache header? The only thing you need to do is either use a specific path or do the same as this service does with a URL at the end.

Of course denying random hosts l.

Should be doable in a few minutes