This app was mentioned in 5 comments, with an average of 1.40 upvotes
I use BikeComputer Pro. It's very detailed, highly customizable, and I don't have any problems with it. It works offline aswell, including (emergency) navigation function and detailed offline maps, which know the smallest of bike trails. The online navigation (must only be online to calculate the route) can use different engines, some optimized for bicycling, i.e. avoiding inclines etc. It works with HR monitors, but I don't have one so I can't comment on that. It has a free version so you can try before buying.
https://play.google.com/store/apps/details?id=de.rooehler.bikecomputer.pro
This by far the best app to use as a bike computer with navigation. I've used it for a couple of years. I stopped using it because my phone doesn't support ant+ on Android 11.
https://play.google.com/store/apps/details?id=de.rooehler.bikecomputer.pro
Just went through the debate of a dedicated computer or this. You can connect cadence, speed, hrm, and if you export the gpx from strava to komoot and then export that and put the file on your phone you'll get turn by turn. Strava doesn't give turn by turn data.
There's a free version but I haven't used it.
I want to get a GPS watch too. One of the Lezynes is the one I want. But it's a bit out of my range, and a smartphone is good enough for my needs. I've been using BikeComputer Pro for a long time. You can download offline maps for it and it has the features that you'll find in more popular apps.