What I can give you is the next best thing: A way to self-check. Most fire extinguishers have both an expiration date and a pressure gauge. You want the pressure to be in the green and the date to be in the future. They usually last 10-12 years with proper care, but you still want to regularly check these things.
My source for this: An inspector, who checked the extinguishers for the pharmacy I worked at back then (was employed or contracted by the pharmacy chain). It has been over 10 years, but it doesn't look like this information is out of date.
In your case I'd search for a company that is certified by NICET [2].
[1] https://www.nfpa.org/news-and-research/publications-and-medi...
[2] https://www.nicet.org/certification-programs/electrical-and-...
It helps a bunch in an emergency when you are not preforming a technical operation for the very first time.
I will concede this may be tricky to pull off in a more urban environment, "Yes officer that's the idiot who lit his garbage can on fire in the middle of the street", in which case do without the fire, or make friends with the local fire department and they will let you do it in their parking lot.
There are small tests recommended each one or two years, but also a more serious test. The bottle will probably need to be tested for an integrity check each five years to see if it can hold the pressure without bursting. Owner can't do this test by the risk of blow and the lack of the machines.
I (in an affluent US east coast suburb) called my fire dept's non-emergency line to ask about this once a few years ago, and they told me this isn't something they do. So who does it?