The latest device you can use with full support is Sony Xperia 10 III, released in 2021. There have been no further releases; the project never really took off and unfortunately it seems that the OS is slowly dying. The Finnish company behind it, Jolla, had a joint project with Russia (Aurora OS), which I believe provided a good chunk of the funds via Rostelecom. With the war everything changed, and in 2021 they had to cut ties entirely with Russia for many reasons: embargos, and many people rightfully not wanting anything to do with "a Russian OS" on their phone. The company had to be "restructured" in 2023.
