Again without diving deep I've constructed a test case that is probably relevant.  I've pasted the diff below because I'm not yet convinced that it is correct (in particular the value for "argv0". This would also require a second test case that does something similar for a venv when using a framework build (the test_venv_macos case seems to be for a regular install and not a framework install)

With this tests case I get a test failure that matches my observations:

test test_getpath failed -- Traceback (most recent call last):
  File "/Users/ronald/Projects/Forks/cpython/Lib/test/test_getpath.py", line 444, in test_framework_python
    self.assertEqual(expected, actual)
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: {'exe[273 chars]/9.8/bin/python9.8', 'base_prefix': '/Library/[381 chars]ad']} != {'exe[273 chars]/9.8/Resources/Python.app/Contents/MacOS/Pytho[410 chars]ad']}
  {'base_exec_prefix': '/Library/Frameworks/Python.framework/Versions/9.8',
-  'base_executable': '/Library/Frameworks/Python.framework/Versions/9.8/bin/python9.8',
?                                                                        ^^^ ^     - ^

+  'base_executable': '/Library/Frameworks/Python.framework/Versions/9.8/Resources/Python.app/Contents/MacOS/Python',
?                                                                        ^^^^^^^^^ ^      ^^^^^^^^^^^^^^^^^^^^^^^^^

   'base_prefix': '/Library/Frameworks/Python.framework/Versions/9.8',
   'exec_prefix': '/Library/Frameworks/Python.framework/Versions/9.8',
   'executable': '/Library/Frameworks/Python.framework/Versions/9.8/bin/python9.8',
   'module_search_paths': ['/Library/Frameworks/Python.framework/Versions/9.8/lib/python98.zip',
                           '/Library/Frameworks/Python.framework/Versions/9.8/lib/python9.8',
                           '/Library/Frameworks/Python.framework/Versions/9.8/lib/python9.8/lib-dynload'],
   'module_search_paths_set': 1,
   'prefix': '/Library/Frameworks/Python.framework/Versions/9.8'}

test_getpath failed (1 failure)





The inline diff (and as mentioned before, I'm not sure if the value for "argv0" is correct):

%  git diff ../Lib/test/test_getpath.py                                                                                                                     (main)cpython
diff --git a/Lib/test/test_getpath.py b/Lib/test/test_getpath.py
index 3fb1b28003..69b469f179 100644
--- a/Lib/test/test_getpath.py
+++ b/Lib/test/test_getpath.py
@@ -414,6 +414,36 @@ def test_custom_platlibdir_posix(self):
         actual = getpath(ns, expected)
         self.assertEqual(expected, actual)
 
+    def test_framework_python(self):
+        """ Test framework layout on macOS """
+        ns = MockPosixNamespace(
+            os_name="darwin",
+            argv0="/Library/Frameworks/Python.framework/Versions/9.8/Resources/Python.app/Contents/MacOS/Python",
+            PREFIX="/Library/Frameworks/Python.framework/Versions/9.8",
+            ENV___PYVENV_LAUNCHER__="/Library/Frameworks/Python.framework/Versions/9.8/bin/python9.8",
+            real_executable="/Library/Frameworks/Python.framework/Versions/9.8/Resources/Python.app/Contents/MacOS/Python",
+        )
+        ns.add_known_xfile("/Library/Frameworks/Python.framework/Versions/9.8/Resources/Python.app/Contents/MacOS/Python")
+        ns.add_known_xfile("/Library/Frameworks/Python.framework/Versions/9.8/bin/python9.8")
+        ns.add_known_xfile("/Library/Frameworks/Python.framework/Versions/9.8/lib/python9.8/lib-dynload")
+        expected = dict(
+            executable="/Library/Frameworks/Python.framework/Versions/9.8/bin/python9.8",
+            prefix="/Library/Frameworks/Python.framework/Versions/9.8",
+            exec_prefix="/Library/Frameworks/Python.framework/Versions/9.8",
+            base_executable="/Library/Frameworks/Python.framework/Versions/9.8/bin/python9.8",
+            base_prefix="/Library/Frameworks/Python.framework/Versions/9.8",
+            base_exec_prefix="/Library/Frameworks/Python.framework/Versions/9.8",
+            module_search_paths_set=1,
+            module_search_paths=[
+                "/Library/Frameworks/Python.framework/Versions/9.8/lib/python98.zip",
+                "/Library/Frameworks/Python.framework/Versions/9.8/lib/python9.8",
+                "/Library/Frameworks/Python.framework/Versions/9.8/lib/python9.8/lib-dynload",
+            ],
+        )
+        actual = getpath(ns, expected)
+        self.assertEqual(expected, actual)
+
+


I may work on a PR later this week, but can't promise anything. My energy level is fairly low at the moment (for various reasons).

BTW. The code in getpath.py, and tests, also don't seem to handle different values for PYTHONFRAMEWORK, I sometimes use that to have a debug framework install next to a regular install.  I'll file a separate bug for that when I get around to testing this.