This may not be exactly what you want, but I use Apache guacamole for this. The client becomes a web browser, and a chromium based browser allows seamless bidirectional clipboard. I use Ubuntu VMs with Mate as the DM and with a few keybinds tweaked it is solid. I use tightVNC as my server which supports dynamic resize, and the soon to be released guacamole 1.6 supports sending dynamic resize (since the underlying libraries are now updated to support it; RDP in guac already supports dynamic resize). How performant is it? I have a single proxmox vm which runs 3 Minecraft instances for our server’s 3 bot accounts (which just stand still) and the desktop is still navigable.

We tried to host it ourselves to save cost, and it’s a beast but it mostly works. It certainly lags behind in features and uses a lot of resources, but when you compare with the cost it’s certainly passable.