Hardware far outlasts software in the smartphone world, due to aggressive chronic designed obsolescence by market abusing monopolies. So I will never buy a new smartphone - don’t want to feed those scumbags. I am however willing to buy used smartphones on the 2nd-hand market if they can be liberated. Of course it’s still only marginally BifL even if you don’t have demanding needs.
Has anyone gone down this path? My temptation is to find a phone that is simultaneously supported by 2 or 3 different FOSS OS projects. So if it falls out of maintence on one platform it’s not the end. The Postmarket OS (pmOS) page has a full list and a short list. The short list apparently covers devices that are actively maintained and up to date, which are also listed here. Then phones on that shortlist can be cross-referenced with the LineageOS list or the Sailfish list, which seems to be exclusively Sony¹.
So many FOSS phone platforms seem to come and go I’ve not kept up on it. What others are worth considering? It looks like the Replicant device list hasn’t changed much.
(update) Graphene OS has a list of supported devices
(and it appears they don’t maintain old devices)
Pixel 9 Pro Fold (comet)
Pixel 9 Pro XL (komodo)
Pixel 9 Pro (caiman)
Pixel 9 (tokay)
Pixel 8a (akita)
Pixel 8 Pro (husky)
Pixel 8 (shiba)
Pixel Fold (felix)
Pixel Tablet (tangorpro)
Pixel 7a (lynx)
Pixel 7 Pro (cheetah)
Pixel 7 (panther)
Pixel 6a (bluejay)
Pixel 6 Pro (raven)
Pixel 6 (oriole)
So Graphene’s mission is a bit orthoganol to the mission of Postmarket OS. Perhaps it makes sense for some people to get a Graphene-compatible device then hope they can switch to pmOS when it gets dropped. But I guess that’s not much of a budget plan. Pixel 6+ are likely not going to be dirt cheap on the 2nd-hand market.
¹ Caution about Sony: they are an ALEC member who supports hard-right politics. They were also caught using GNU software in their DRM shit which violated FOSS licensing in a component designed to oppress. Obviously buying a new Sony thing is unethical. But perhaps a 2nd-hand one is fine. It’s still dicey though because the 2nd-hand market still feeds the 1st-hand market and rewards the original consumer. Sometimes it’s clear you’re not buying from an original owner, like someone on the street with a box of 100+ phones.
I'm not sure what you mean about "alternative process" for updates. In the chart you posted, the US got 466227 updates in 1 day which is about 14 million per month if that happens every day. If they are 100 bytes each (no idea if that is realistic), that's 1.4GB a month for the whole US. Right now a new map download is something like 1.1GB for California alone. California is the biggest US state (not in terms of land area but certainly in terms of roads) but the whole US might be 10x or 20x bigger.
I'd say OM is less in need of new features than of getting its existing features working solidly, warts ironed out, etc. The one major feature improvement i could see is getting the voice directions to include street names, but in practice it's not that important, at least in my usage.
Google Maps has a sometimes useful feature that an offline app like OM can't possibly get, which is routing and ETA calculations based on realtime road and traffic conditions. I don't rely on that very often, but on occasion, it really helps. Unfortunately I suspect that much of the traffic data comes from the devices themselves phoning home with their locations, and only Google and Apple have enough devices out there to usefully do that.