don't forget that there are a number of offline map systems that you can have as a backup on your phone or tablet. In tricky urban settings, I have even used google maps on my phone, but just listening to the voice command (so screen off) with my phone in a small toptube barbag.
This reminds me there are two pretty useful apps to consider if you have a phone:
1. MAPS.ME or the older version as Organic Maps. This is an offline map. The cycling instructions are junk and I don't use it for offline routing. Instead, what I've found helpful is a quick offline check of "where am I?" In a confusing urban setting you will likely have a cell signal as well but if you are either saving data or in a place without cell signal it can sometimes be helpful to sort out your location.
In both cases I don't have the phone on continuously. Instead it is always turned off but then on demand I'll turn it on to check my offline map.
2. iOverlander. While the primary audience is more towards overland vehicles and motorcyclists - this can be a useful app to find see camp sites or services. There tends to be a community that keeps things up to date. You can get an idea of the type of info by looking at the web site and then think of having it on your phone. It works better when there is a cell signal though you can still get info w/o maps since the database has been downloaded.