There are other ways you can enhance the SR/SR+ navigation that might interest you. The first is to simply use your phone. The Model 3 has a pretty good place to put your phone, plugged in so you won't run the battery down. You could then run whatever navigation app you like on the phone and listen to its directions. This has the drawback, though, that the map directions wouldn't be nearly as visible as those on Tesla's screen. This likely wouldn't be a big deal if you're traveling in an area you know moderately to very well, but it could be a drawback if you're traveling in areas you don't know well. The Model 3 displays its map constantly (although it can be hidden behind other windows), so you'd be able to see a map pretty easily. You'd need to look down further from the road to see the markings indicating the apps suggested route, though.
There's also a Web site called Tesla Waze, which gives you access to Waze's problem-reporting features and a map display via the Tesla's built-in Web browser. This tool does
not provide turn-by-turn directions, so it's more useful as an information source about traffic conditions and road hazards when you're driving in familiar territory than as a guidance tool. Here's a video on its use:
I've never used my phone's navigation apps in my Tesla nor used Tesla Waze, so I can't comment from personal experience how either approach would work. It must be possible to combine these with Tesla's own navigation -- if nothing else, you could enter your destination into both the Tesla's navigation and your phone and decide which route to take when they disagree. In fact, if you wanted to use Navigate on Autopilot but still see what Waze, Google Maps, or whatever has to say, you'd pretty much have to do that, even in a top-trim Tesla.