Other reminder actions for events in Mozilla Lightning / Android Calendars (e-mail reminders)

Question

I'd like to get email reminders for some of my events. Apparently, that's not currently supported in Thunderbird/Lightning (or Android).

I have a server that can access my calendar, if I can add custom reminder action in either Lightning or Android (ideally, both), a Python script on that server could easily do the job. But apparently neither of those two calendars supports adding custom reminder types?

There is an old Lightning addon to add custom alarm types, but it doesn't even install on recent TB versions.

Any ideas on how to approach this problem? Are there other addons I should be using? Should I use an alternative calendar on Android that can do this?