it is not necessarily the compressor that is inaccurate it is the hose that causes the issue. having a regulator at the end of the air hose will be more accurate. I use one very similar to this.
Tire Inflator w/ Dial Gauge
I also have this one same brand but my button is in a different spot to relieve air.
Moroso 89560 - Moroso Tire Pressure Gauges - Overview - SummitRacing.com
After each use I drain my air tank of water to make sure not putting it into the tire. If you don't have a large compressor and rely on a shop to getting your air I would suggest a small portable compressor like mentioned already.
to see if it is accurate I use my wifes Cadillac with the tpms the on board computer tells you tire pressure. Comparing that to the moroso and the in line gauge it is within 1 lbs of the in car monitor when cold.
Look at summit racing they have tons of gauges 197 is what I got in my search
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