Is there a dev friendly alternative to Gmail, Outlook, etc.?

I have had this idea in my head for a few months for an open-source email client, but i want to know if one exists already.

I'd like to:

1. Add my email providers like gmail, outlook, yahoo, apple mail, etc and manage them in one place

2. Make email aliases that I can manage and delete. Like firefox relay

3. Navigate with my keyboard like in an IDE

4. Write custom automations like Arc browsers Boosts but for automating my email

5. Write custom filters and rules for certain emails like spam, one time codes, and things like that

6. Self host with my own domain and customize the UI to my hearts content

I know Thunderbird lets you add multiple email providers, but it kind of doesn't do it for me. Does something like this exist? Is someone building it?

If not, I'll probably just build one myself.