Another big plus is that it will parse a GPX file into a course on the watch so if you stick one into NEWFILES that you have found on the internet somewhere, you don't need to try and convert it to a FIT file first.
I put a Strava route onto my watch this way as another test.
There is a great ConnectIQ called RouteCourse that I have been using (https://apps.garmin.com/en-US/apps/b7efc9ca-5446-4e1c-bc53-474e97f376ac). It imports courses from all types of sources in the web interface and then when you want to navigate a course you can open the ConnectIQ app and just download it to the watch. I typically use Strava or RidewithGPS for course and it just imports those without any work at all.
There is a great ConnectIQ called RouteCourse that I have been using (https://apps.garmin.com/en-US/apps/b7efc9ca-5446-4e1c-bc53-474e97f376ac). It imports courses from all types of sources in the web interface and then when you want to navigate a course you can open the ConnectIQ app and just download it to the watch. I typically use Strava or RidewithGPS for course and it just imports those without any work at all.
In addition if you want maps on the 935 you could try DWMap (same developer as RouteCourse), but it is not yet compatible with the 935, but gives same functionality, but also a map as well for the course.
I really like RouteCourse, simplifies everything for me and I have all my routes in one place and you can share routes through their platform as well for group rides. BTW this also works on Edge devices as well and I also use it on my Edge 820.
As for the turn-by-turn, you're not getting true turn by turn like on the Fenix 5X. Your course basically has to have the info on turns already embedded in it. No idea if Garmin Connect courses include this now but they didn't used to. That was a main reason for needing to use 3rd party apps that do create courses with this info.