Add option to combine feeds of my accounts

**Is your feature request related to a problem? Please describe.**
For example I have an account on `lemmy.world` and one on `lemmy.dbzer0.com`. But when I'm logged into the `lemmy.world` I don't see the stuff that's on the other community. It's annoying to keep switching the accounts.

**Describe the solution you'd like**
Title, really. Please add an option that allows the combination of the feeds. I want to see everything across all my accounts in one place.

**Describe alternatives you've considered**
The "All" and "Local" options are not what I'm looking for. they only include posts of the current account.

**Additional context**
I've read [here](https://lemmy.world/post/1084963/879963), that the "[Liftoff!](https://github.com/liftoff-app/liftoff)" client allows exactly what I'm asking for, but unfortunately it's not available in my Region on the AppStore + the app seems to be unmaintained. The last commit was 2 years ago.