I have a subscription service from komoot for maps. Is there any GPS device that supports offline maps and GPX, preferably with android OS integration. Example scenario would be: Use an android based GPS apps in that Navigation device. Basically, I would like to avoid using my android phone for navigation, while hiking big trails.
Have a look at an application called Avenza PDF Maps. Avenza allows you to download a host of free (can not free) maps onto your tablet or smart phone. Since Avenza is displaying the map background and your location on the map only using the device and the devices GNSS you do not need cellular coverage to see your location. If you are in the USA you can download any USGS topographic map for free. GPX support? This is planed for a future Avanza release. You could bring your GPX data into something like QGIS and create your own geo-spatial PDFs. If that is the case have a look at GIS Stackexchange for help there.
If you need more GPX support consider BackcountryNavigator which allows you to download data for off-grid use and import GPX files.