[0] https://www.androidauthority.com/pixel-linux-6-1-android-15-...
AFAIK outside the Pinephone and Liberem 5 no hardware manufacturers explicitly target this and only 10 year+ old Qualcomm (other vendors such as Freescale tend to behave much better) SOCs have open source graphics drivers because the SOC vendors themselves often refuse to support their own hardware.
Google is able to do this because they build their own SOCs (probably because they got tired of being jerked around by Qualcomm) but still don't merge their stuff upstream (or at least they don't last I checked.)
Starting 20th of June this year (so 3 days ago) every new phone released in European Union will need to have software updates for at least 5 years from the date of the end of placement on the market. This might be the first one released under new regulations. Also looking at Fairphone's history it looks like they really support their phones for a long time.
This is why using SOCs with poor support and closed drivers like this is a terrible idea.
Many mainline supported SOCs are unavailable to a company like Fairphone, which only produces a tiny amount of phones (less than 50k for the latest and greatest model). CPU manufacturers aren't going to waste time sending their top-end chips to some small company when Samsung can pay more per CPU and can take shipping containers full of them. That's also why F(x)tec phones come out with such outdated processors. Small companies will have to make do with whatever niche products are for sale in low quantities.
This is software, not hardware. It is ridiculous to pretend it is ok for a phone to artificially stop being useful after just 5 years simply because the vendor won't give software support or even provide the necessary documentation, source code and keys for the community to do.
At least this is 5 years from "the end of placement on the market". So more realistically it should be around 7 years from release.