The challenge: a few users setup would just run on any system both Linux and Windows the key limiting factor is the Storage and Database, here we could just copy OpenEdge12 just running core will be in most cases not be helpful, as you likely need connectivity to other systems as documented in the https://www.notion.so/build-one/c5dede6be8da40d691acc54d140563a9?v=e5de0e84718d4ab2a51a38a05dfaeda0&p=33c8905f674a484a8a3526a39bc5ebe1&pm=s, these will all have different memory and storage footprint characteristics
In short, for a PoC anything will do, I can compile the bare minimum requirements, I suspect these would be as wild ass guess: 16GB RAM 10GB free Disk Space 2Ghz 8 Core CPU Gigabit Network connectivity to their Storage, Rest Services etc. Any thoughts on how fine grain you would need it? If you needed to know what configuration need we have for a Production Installation of B1, with a SAP backend, 1000 concurrent users, average SAP query size 20k, average concurrent queries per second 10, we could load test and come back. What is for the customer critical to know? Do you have examples of granularity from other vendors as to how fine grained we need this? This seems similar to the SLA topic, you can tell engineering what you would expect we could be able to share, then we can say if we need to test such a configuration to confirm or if we feel confident from the hip to say, sure we will be ok on that platform.
Also see
Rendering Engine im Browser vs. Terminal Server (=begrenzte Ressourcen)