Even iPads with a cellular modem only have data enabled. Calling anyone, including 911, from an iPad requires some setup of Wi-Fi Calling ahead of time with a paired iPhone on the same Apple account: https://support.apple.com/en-us/108066

There's Proton Mail Bridge for paid accounts: https://proton.me/mail/bridge

Okay but now I need an always-on computer running an additional app.

Huh? You run it on the same computer you are checking your mail from.

What do you do on a phone?

I was really curious to see what Gerbils! is in the Applications folder, but that just triggers a hard lock up after the splash screen. I see the menus are "Environment", "Rendering" and "Camera" though.

Gerbils! is a demo app for QuickDraw 3D where gerbils are racing on a roller coaster track (or similar…it’s been a few decades). It existed for classic Mac OS too (I remember playing it on a 6100)

https://status.proton.me/incidents/kzklhrdg6hxp for this particular incident.

Found it. Click on "Global Outage" In the orange top bar. Hard to find when there are three different colors for hyperlinks on one page.