When I debug React-Native the source files on the Page tab in devtools never groups the files by folder on Windows 10, it shows a list of all js files (including all files in node_modules).
I created a basic test app using:
"dependencies": {
"react": "17.0.2",
"react-native": "0.65.1",
"prop-types": "^15.6.0"
},
Ran: react-native run-android started the debugger and see this:

