@jamiemachine5 @TooBarFoo — your setups are pretty close to what I built my integration for, so it might save you some time.
I have a custom integration specifically for multi-zone hydronic UFH: Underfloor Heating Controller. It handles several of the things you’re both working through.
@jamiemachine5 — on your goals list: the integration does per-zone PID control tuned for screed thermal mass (anti-windup, EMA smoothing for noisy wireless sensors, minimum run times to prevent short cycling), weather compensation via a two-point heating curve, and pump/heat request coordination.
@TooBarFoo — you might find this applicable as well, as your use cases are very similar to what I’m running myself.
Others might also find the Tasmota relay configuration guide relevant if you’re running Tasmota on your relay boards — it covers PulseTime as a dead-man-switch so valves fail closed if HA goes down.