Flow meter

Have something that can clamp on to a belt or pipe to provide statistics on how many units/items pass through it per month/3 month/etc.

I had same idea. Especially for water, diesel, coal it could be really useful.
Just implement simple https://en.wikipedia.org/wiki/Moving_average and let player to choose number of months eg. 6, 12, 24

Even if it was too complex to implement avg stats, say for for mixed belts. I think a slightly reduced monitor offering simple status would still be very useful.
- flowing/moving
- not flowing/moving
- empty
- full
- and the same stats we get from storage alerets like < 50% full
Right now, to get an alert for full/empty on a pipe r belt we need to add storage and set alerts there.

Please have a look it suits: Throughput Monitor & Flow Meter mod here https://coigame.com/Mod/1089/Throughput-Monitor-Flow-Meter