Use APKPure App
Get Soft Keys 2 - Home Back Button old version APK for Android
Don't worry that the buttons are broken, developer brother is here :D
Activate the on-screen keys, enjoy it! Don't need root.
advanced users, visit my other app for more customization : Soft Keys - More Settings
https://play.google.com/store/apps/details?id=com.dogusumit.softkeys_moresettings
source codes : https://github.com/dogusumit/SoftKeys2-HomeBackButton
This app uses Accessibility services.