I’ve done some poking around today wrt managing gas usage, and I think I’ve come up with a reasonable idea?
You can buy ‘mass flow controllers’ which are are a mass gas flow sensor + valve. They get super expensive if you blink but new ones can be had for ‘reasonable’ prices. This one is 0-10L/m, good operating range, valve leak rate is exceptionally low (Helium leaks at 5mL a year), provides both flow output and flow control input on a 5vdc analog. So you could throw a gas bottle in a cage, plumb this onto it, open the bottle valve and leave it open and let the MFC do the work.
You can also find them secondhand commonly: https://www.ebay.com/b/20-SCCM-Maximum-Flow-Rate-Mass-Flow-Controllers/184061/bn_87945361?rt=nc&_sop=15 but it can be hard to find the datasheet or manual for them.
I think this is kind of a one-stop-shop to solve gas metering and control. with a basic micro to control the MFC you can both meter and control output. Considering what we spend on gas this would let us manage and recoup excessive use.