According to my tests w/ 3040, ThinOS 9 will not change anything (or event make things worst. The good old ThinOS 8 RDP stack seems to be very well optimized).
Except for Zoom because Zoom now provides a ThinOS companion package for AVD client (RDP) to offload video & audio to the Wyse. Which is working very well, at least on 5070s.
When there is no offloading (barebone AVD / RDP), then your main concern is the CPU load on the server and maybe the network bandwidth if you’re not on 100Mb/full minimum.
So, First, provide plenty of CPUs to your terminal servers. I’d say, one CPU per “full desktop” user.
Second, if bandwidth is not a concern (100Mb/full on clients and 1Gb/s or more on the server) then adjust the multimedia environnement to lower CPU on the server side.