I've been using FindMyPhone (f-droid repo) for many years on LineageOS. My spouse will text a pass-phrase to my phone # and receive GPS coordinates back in a reply message.
That app is now 7 years old(!), so I'm trying to set-up Dimitrios Diamantidis' "FindMyDevice" (f-droid repo, https://gitlab.com/Nulide/findmydevice ). It also offers more features for remote lock/wipe.
If I access Settings->Apps->All Apps->FindMyDevice->Permissions, I see that SMS is "Not Allowed". When I select the SMS permission, "Don't Allow" is checked, and the "Allow" button is grayed-out. Attempting to select "Allow" gives an error message "App was denied access ... Access to this permission can put your personal and financial info at risk... Learn how to allow access "
The last bit "Learn how to allow access" looks like a link, but clicking it does nothing.
Similarly, within the app, there is a permission screen to grant needed permissions. Clicking the "Grant" button next to SMS does nothing (no granting of permissions, no error or prompt)