On some derailleurs, you can remove a pulley to get the chain off as a closed loop. Still a pain, but in my case would save a $5 master link that isn’t supposed to be reused at all (sram 12 speed).
You’d also need a hole in your seatstay to remove the chain unbroken. (Some frames designed for belts have the ability to remove part of the seatstay, but it’s not common.)
With the wheel out and the bike upside down, you could put a cooking plate and pot on a stool next to the bike and immerse your chain while still wrapped around a stay. (You'd have to do it in two phases, of course, unless you have a really big pot and immerse half the bike...)
