I think they should have a larger responsibility than that, but yeah I absolutely agree that once devices are no longer "supported", the manufacturer should be required to relinquish control to owners in a safe manner (e.g. Android unlockable and relockable bootloaders).

Same goes with multiplayer game developers. If they wanna stop hosting servers, they should be required to release the server software in a manner that makes it possible for me to set it up for myself to keep playing the game.

They should be required to place the keys and the initial software build into escrow, so either when a fixed time has elapsed, or they have been found cupable for a breach of an applicable law (e.g. if they stop providing software updates).