I just set up my gps data to feed into chrome this week. I am no expert, so it was a bit… intense. A good place to start is here: https://forum.clockworkpi.com/t/gpsd-chrome-extension/18011?u=casperer007
It’s a beautiful little set up that lets you use your gps in multiple apps without clogging up the serial port by using gps-share and gpsd.
Getting gps data into firefox was as easy as setting up gpsd for me. Your /etc/default/gpsd you posted looks pretty good aside from the “/” in tty/AMA0, should just be ttyAMA0.
However, getting gps data in chrome involves loading in an extension yourself. You can look at that link if you are interested in enduring the same pain I’ve suffered
but that little blue dot on the map is worth all the effort in my book lol