I had a similar problem with needing a more powerful computer but not wanting to idle it all day long. The desktop however supported Wake on Lan, and the router

I had a similar problem with needing a more powerful computer but not wanting to idle it all day long. The desktop however supported Wake on Lan, and the router stays on 24/7 anyways. So I ended up configuring SSH and software to send the magic packet on the router, and then sleeping the desktop. SSH in, send the wake up packet, then remote into the desktop. Put it back to sleep when I was done. There's still some quirks. You can't wake the desktop from a shutdown state, only a sleep state so you have to be a little careful only to put the desktop to sleep. But worked remarkable well and didn't require any additional hardware at least for me. The data transfer portion I don't know if I can offer any good ideas for you. My workflow was to treat the desktop as the primary workstation most of the time. Be curious to hear your experience with eGPU as well.