Thanks for the answers. Very helpful.

I think I'm going to just do a new $19/month minimum plan to check out Freedom's coverage. Thanks to warnings here I won't consider moving my existing service over yet. The OpenSignal app on my phone says that while connectivity is good where I am, speeds are almost a quarter of my current provider (Koodo/Telus). Freedom is making some noise about 5G and I believe they have either bought or are going after some 5G spectrum. But I don't know what to make of it yet.
 
I had never heard of GrapheneOS; interesting that it *only* runs on recent-ish Google Pixel phones.  As the battery on my OP5 starts to age, I suspect I'll be looking at a Pixel in the not too distant future, certainly of interest to hear what's up with alternative phone "firmware" these days, particularly as it's difficult for them to keep up with hardware evolution.  CM and LineageOS had history of supporting lots of devices; Lineage has been hurting in that regard <https://download.lineageos.org/>  They used to support a wide variety of Samsung, but no models later than about 2017 have been supported, no LG past about 2016, and such.  If there's reason to expect better from GrapheneOS, that would sure be nice.  (That tells you some of the kinds of questions I'd hope might get answered ;-) )

"Why just Pixel" is answered in the FAQ and in more detail on Reddit. The main reason that I can extract is this is not your garden variety XDA alternate ROM, and not every phone can be locked down as they demand. GrapheneOS replaces boot and firmware code and requires you to relock the bootloader at the end of the installation; that's something I haven't seen before.

Customer service said I'd made that change from my phone when I enabled phone over wi-fi when that was available instead of LTE over the sim and they couldn't change it back. I even reverted to the original distribution OS but no joy on incoming calls after that glitch.

Unlike Koodo, Freedom has some brick-and-mortar stores and I hope the one nearby may be more helpful than a call centre. That may be wishful thinking.
I notice in the GraphineOS downloads the pixel 2 walleye release is supported. Thats the Pixel core base I'm running on my Nexus now, so I'd be interested in hearing about your install experience, to see if I can further kludge/extend the life of my own Nexus. 

Because of the issues above (they replace far more than the system and user partitions) I'd be careful. I think they're looking for exact hardware matches, and note that there's no support for the Pixel 1 and only "legacy" support for the Pixel 2.

I recently bought a used Pixel 3a for $200 just to try Graphene. This is part of a personal experiment to see how private I can get with a privacy-focused phone, no Google apps and a new Protonmail alter-ego email account just made.

Installation was fast and flawless from my Kubuntu box. it doesn't require TWRP or use recovery mode; everything is done using the "fastboot" comment and fastboot mode on the phone.

Challenges so far are in setting up notifications, and to find apps that don't require Google Play Services to run. Still, there are some interesting finds, such as a hardened Chromium-based browser called Vanadium (which is more lightweight than Bromium because it can take advantage of a hardened OS).  Users are warned that Firefox is way too insecure and should be avoided. I haven't yet set up email or calendar, but Signal and Telegram work fine. A few games that I've tried don't work. But there are two great apps, NewPipe and Aurora Store, that anonymize access to YouTube and the Google Play Store respectively.

So far it's a battery beast, lasting many days on a charge. While it's not checking email or calendar updates yet, it's also not spending any effort telling Google where I am or what I'm doing.

It's an interesting project to be sure.

- Evan