Not really solving all your cases, but I found tmux (or herdr) on a home server works pretty well. I just ssh into my home server and continue where I left off with the same claude/opencode open.
On a longer term, I think "assistant" style harnesses might help here, like vellum.ai. I no longer use that, but I asked it to create an ACP proxy through iroh (basically tailscale but on the application layer), and it managed to control claude on another device of mine. A friend did similar stuff with tailscale.
I have started writing a hobby harness with a web interface where I would like to support this "ACP proxy" mode natively, and also to make the models aware of different devices in some way and "move" work between them.
I basically do this, tmux via tailscale. But, I often get inspiration and want to jump into a webapp from my phone, or review.
I've been playing with pi and the remote webui extension. I don't love it; it has a lot of chrome that obscures what I want to do. I just want a simple way to review the progress so far, and keep tweaking with minimal setup. Then, jump back into tmux when I'm back on my computer.
On a longer term, I think "assistant" style harnesses might help here, like vellum.ai. I no longer use that, but I asked it to create an ACP proxy through iroh (basically tailscale but on the application layer), and it managed to control claude on another device of mine. A friend did similar stuff with tailscale.
I have started writing a hobby harness with a web interface where I would like to support this "ACP proxy" mode natively, and also to make the models aware of different devices in some way and "move" work between them.