This is also my favorite mobile RSS app. I am currently using it with Miniflux.

I have had positive experiences with both Radicale and Baikal. I am not sure about the Home Assistant integration, but they both use CalDAV, so I would be surprised if there wasn’t a way of connecting them. iOS has native support for CalDAV, but Android needs the davx5 app (free on F-Droid).

This is where I thought it was going as well.

Lemdro.id

I would recommend looking into an aliasing service such as Addy or SimpleLogin to use a different address for every service, which then gets forwarded to your main email address. This way when you get spam emails, you know who sold your data or had a breach, and you only need to create a new alias and change your email at one place instead of everywhere.

Runbox had contacts and calendar when I used them a couple of years ago, so I would assume it still has them.

I just run some simple services such as Audiobookshelf or Wallabag behind a reverse proxy. After reading the other comments, it does not look like there would be any benefit for my use case.

Yes, I have always used a reverse proxy which seems to eliminate the need for multiple IP addresses. It seems like having multiple IP addresses just creates additional cost and complexity, but I have seen many VPS providers offer multiple IP addresses, so I was curious if there was a use case that I was not aware of.

Yes