If you self host both Lemmy and Ntfy, you can enable Ntfy's SMTP receiver, and have Lemmy send emails to that port. It's not well formatted for Ntfy but it works. Anything Lemmy would have sent an email for will be sent to Ntfy, and Lemmy thinks it's sending an email.
I just got this set up for myself and it works pretty well! You just need to use a specifically crafted email address with a token in order for it to work.
However, this is only really viable for single-user instances. For myself, this is the perfect solution. But for others with more Lemmy users, unless you want to be manually managing tokens for all of your users, this is not a good solution.
If you don't self host Lemmy, I guess you could still self host Ntfy as an open email server and get them that way, but that sounds like it could get messy.
But yeah, thanks for making Ntfy. I usually use Gotify for my self hosted notification needs, but I needed something with SMTP support so I could use it on Lemmy. Came across Ntfy by chance, and holy crap dude, it does everything!
I don't really self host a lemmy instance so I ended up taking a different route (admitidly janky but reliable).
I have a mac mini running 24/7, I enabled lemmy to send notification emails. On my mac I have the mail app set to automatic refresh and have a set of rules which search for lemmy instance as sender and subject contains reply. When mail detects it I have an apple script run a mac shortcut which checks my inbox latest inbox rss extracts the text and sends a ntfy push. Admitedly there are better ways to do this probably (than relying on shortcuts and apple script) but it works π«
Also I have the link set to open wefwef on android (open in opens webapp) on ios I have it run deeplink to a shortcut which opens wefwef in webview