if spoofing already enabled in recovery image:

usually it should just require the following three steps:

• download magisk apk from github (topjohnwu repo), rename to zip
• enter recovery mode (hold power+vol up+home, release power on first vibrate)
• choose apply update, do sudo adb start-server sudo adb sideload magis.zip > wait for it to install
• then reboot
• go to microg and click the checkmarks and it should ask you if it should be spoofed

if new/stock recovery image:

do this whole procedure

flash the two resulting files with magisk (installed like the three steps before)

reboot and hope for the best

go to microg settings and click on the spoofing test thingies until everything has a checkmark