Are there any chances to use a RPI 4 with your Image as Server and Thin Client together? Meaning the Browser in Knock-Mode for User Interaction.
You can have D2000 server + thin client (firefox) on a single RPI.
Back in 2018, we tried several scenarios using RPI2 and RPI3 - see the blog https://d2000.ipesoft.com/blog/d2000-and-a-raspberry-pi/
I don’t see any reason why RPI4 couldn’t handle both workloads, as it has more CPU power (and optionally more memory) than RPI2 + RPI3.
To add to Helpdesk’s answer, when you look at our RPI image installation manual, you can notice at the end a section dealing with the installation of a graphic interface and the Chrome browser, which hints at exactly the use that you asked about.