>>(Microsoft has not set any kind of “minimum bandwidth” requirements so far).

I wouldn't expect it to be substantially different from that for Azure Desktop. https://docs.microsoft.com/en-us/azure/virtual-desktop/rdp-bandwidth

TLDR: the RDP protocol is very economical on bandwidth, turning window moves into move/redraw instructions in the client rather than full screen refresh. Seems the largest use would be from streaming 4K video or moving big files between client and cloud desktop.