The main initial benefit for the project is to have completely free embeddable web maps hosted p2p (using ipfs, hyperdrive, webtorrent) where you can entirely customize the rendering. Then later the benefits of the fully symmetric nature of the database will start to make more sense and the project has the potential to become less centralized on open street map servers and data. For some prior work that I and other people who work on peermaps have worked on check out https://mapeo.world/ and this very old writeup I made about an early version of the osm-p2p database. The experiences of working on that project and prior versions heavily informs how the current peermaps stack works.
You can check out a more up to date version of the progress on this talk we gave for speakeasyjs recently: https://www.youtube.com/watch?v=P7X7C-door4
Or here is a slightly old slightly broken version of panning across a processed version switzerland using the end-to-end stack on my laptop (it looks better now) https://www.youtube.com/watch?v=gHEmmQ6GnDI