Smart heating wiser or diy

Hi all, this is my first post. I have a simple ha setup and am looking at the heating setup now. Ive recently had my heating system updated (new boiler, radiators and hot water cylinder) as the old one guzzeled/wasted alot of oil. I’ve got a single zone oil heating with a hot water tank. There are about 25 radiators in total with dumb trvs and a nest thermostat.

So I’m unsure if I should get the wiser system and put smart trvs on most rads. My concern is I don’t want it impacting my wifi channels and I already have a zigbee network. You don’t appear to be able to use external temp sensors for the trvs, and seems a bit closed solution with no opentherm support. But the scheduling looks great with the ha add on too.

Or do a diy style using home assistant to do all the scheduling/control and hive trvs on the rads. I found this automation (Smart heating scheduler for Home Assistant (extra: multi-zones version)) which looks good. But are there other better and easy to use automations?

Is there any recommendations on the best way?
Sorry I know this is a broad question but don’t want to spend a lot of money and go the wrong route.

Many thanks