@wavoigt We have tested HMI terminals from weintek like this one https://www.unipi.technology/weintek-mt8051ip-p198?categoryId=29 via Modbus RTU (RS485). Works well but the SW setup is a bit complicated.
Mervis has recently gained BACnet server support so you can connect higher verions of Weintek displays which support BACnet with Neuron or Axon via BACnet/IP
Alternatively Mervis has a web based HMI so you can also use this with any web browser while on the same IP network.