Update: a two-pronged approach starting with a Fairphone 6.
I emailed Guido, a friend in Germany who worked on the Librem 5 for Purism and who runs the Phosh effort. Guido and I worked (remotely) on the SGI Linux port at the turn of the millenium. He paid me a visit at my office when he was in town for DebConf 2002 and configured Debian for me, which at the time was launched with a series of incantations, to boot directly from the Indy's hard drive.
Guido recommended waiting a bit to get a daily driver, but suggested the OnePlus 6 or 6T as a spare device for installing Linux because of its wide support. Sendero Linux in Virginia sells the 6T refurbished with postmarketOS pre-installed for (US?) $160 (
https://senderolinux.com/product/oneplus-6t-postmarketos/) but they can be had on eBay for C$100-200 and I *want* to do the installation myself. (Also having just paid $50 to get a complimentary copy of a book from Spain that was routed through NYC into Canada, I'm not keen to try to get something like that across the border.)
I ordered the Fairphone on Saturday from Clove Technology in Dorset. After a flurry of order confirmation activity the channel went silent until open of business on Monday when Clove and the courier both put the phone in Southampton, estimated delivery the 29th. Refreshing the tracking page hourly told me it was in the depot at Heathrow and then on the tarmac at Heathrow for three days, when it suddenly materialized in Scarborough yesterday morning (via ley line?). I got it in the afternoon.
The Fairphone does wifi calling on Freedom and I'll dual boot Linux on it when I get a chance. In the spring I'll get a OnePlus to run strictly postmarketOS and follow the porting effort. It will be the first time I've had a chance to play with an emerging port since the ASUS Transformer T100TA ten years ago.
Mike