To get the Android P screenshot editor on a non-Android P device you will need to download a separate screenshot editor called “Markup”. Thanks to the XDA member Quinny899 who brought this cool tiny app that works perfectly on any non-Android P 64-bit Android device and even some 32-bit devices to take, share and edit the screenshots.
Here is all you need to do to get it running on your device.
1- Download the APK from here
2- Install the APK like you normally would
3- Take a screenshot and tap SHARE
4- Select Markup from the Share menu
5- Edit the screenshot with the new tools
This sounds pretty handy tool for sharing and editing your screenshots on any of your Android devices. Do let me know if you find this tool helpful for taking and editing your screenshots on your Android device.