Do you mean something like this:
https://www.amazon.com/GrillPro-00030-Magnetic-Level-Indicator/dp/B000FHZ33C
It's available now but reviews are mixed.
The gauges dont do anything all they tell you ten min. before you run out .the preasure is the same in a containers weather you have 1 gallon or 3000 gallons .Try this works on tempeture https://www.amazon.com/GrillPro-00030-Magnetic-Level-Indicator/dp/B000FHZ33C/ref=sr_1_8?dchild=1&keywords=propane+level+indicator&qid=1615458022&sr=8-8