Can you share the current state with regards to basic functions (phone calls, SMS, mobile data)? Does it work reliably?

Phone calls and SMS work fine (but I don't use them much), mobile data also (and I do use it a lot). Rarely, typically during the use of mobile data, the modem disappears. Reboot always helps. Telegram and Firefox are somewhat slow but generally work reliably. Even calls on Telegram work (with the sound coming from the speaker). Noscript helps a lot. Calendar is not very usable. Heavy usage with high brightness can drain full battery in a couple of hours, but suspend lasts more than 24 hours.

I have a pinephone pro sitting idly until I find the time to install an OS to try on it.

I'm keen to try sailfish, I had a jolla in the past and really liked it.

At the same time, I'm weird enough that I want to use the terminal on it wherever possible! For calendar I was thinking of using calcurse.

Pinephone users don't tend to mention that the phone is about as powerful as a Galaxy S3. So keep that in mind.

The Galaxy S3 could do everything back in the day, it was and still is plenty powerful. Banking apps, messaging apps, social networks, web browsing, etc. Of course it won't do fancy real-tike Snapchat filters and AI image recognition, but if Android 4.4.x was indefinitely maintained I would have zero problems using one today.