At least on the Etrex 30x you just use the patcher to use jnx files.
You can use city navigator nt (not ntu) without any patching .
The etrex 32x should be the same. As far as I know it is more or less the same device only with 8Gb internal memory.
They are super slow, special with big maps .
Also, if you have more than one map in the memory (internal or external), even deactivated, when searching on a POI it will search on all the maps.
On the bicycle , it’s auto routing with Garmin maps is not that good. With openfietsmap lite maps it gets better.
Wouldn’t use it in a car.. Mobile phone gps are much better.
For me the etrex makes sense due to the joystick (in bike when it rains touch screen may not work well, and also with gloves it can be tricky) and battery life/running on AA batteries .
Hope it helps