Ive been using 1秒マップ.
ITs avalbile int he google play sotre and apple store (japan side only).
Heres the google play link https://play.google.com/store/apps/details?id=jp.growth.pgo_map_android&hl=ja
I keep going to the Play Store page - https://play.google.com/store/apps/details?id=com.nianticlabs.pokemongo&hl=en When it no longer says "This app is incompatible with your device" I'll know we're good. It's faster and (for me) less distracting than the app. ^.^
一秒マップ is by far the most popular around here now. I think Pgo shut down recently, but I don't know if it was only the website or the app too.
This https://play.google.com/store/apps/details?id=jp.growth.pgo_map_android ? I don't know what to tell you, it works fine on my Google Pixel (Android 7.1.2). I'm not the author and I've seen countless other locals using the app on Android and iPhone alike around here.