Yes you’re right. At least when using PTVO firmware, all math has to be done in the home Assistant sensors you define. This is a great project which has everyrhing you need for it:
PTVO does support a number of I2C sensors, using these is straight forward, the device will report e.g. temperature, humidity…
Most wind meters will use a reed switch. The PTVO firmware can count them and report that count.
If you’re happy with a device that constantly needs power and does basic things, temperature, humidity, pressure, wind Speed, rain and so on you’ll be fine with the free version.
As soon as it’s supposwd to be battery powered, you’ll need the power saving mode which is a premium feature. Also counting analog inputs does not work in power saving mode.
I did a variation of the above weather station using a LiIon cell and a small solar panel (which may be overkill), it does not give you real time information but averages over 1 minute intervals and does involve a bit of soldering, you can find it here: