I’m not running zigbee, I use Wifi, but FYI you may be able to convert to Wifi with the right USNAP for appx <$50. Then I suspect you will have access to the Filtrete gateway for remote management by any browser, if you dig remote exploit vulnerability. The gateway and the corresponding phone-app are pretty decent - not as good as Ecobee but pretty good for 5+years ago. And geko@ST made a Wifi driven DH that works well with ST at the moment, simultaneously with internal schedules if any, AND the gateway. Maybe it’s too connected.
I don’t think zigbee or zwave will provide remote access via the gateway, just whatever hub+app with which it is paired .
EDIT - if you got yours cheep, maybe it is already paired to some previous hub, so you have to reset before pairing to yours. Most zigbee devices, I expect to reset by holding “the button” while inserting the batteries or connecting power. The manual will specify the procedure