linux file permissions as user cannot access file

Question

I cannot seem to open files that should be owned by me... I feel very silly, and a bit like im losing my mind, I don't know what is wrong... but i must be missing something.

# Example shows that all files in directory are owned by user2 with 664 permission
$ ls -la /home/user1/filestore

total 2788
drw-rw-r--    2 user2     user2   2    0480 Jul  2 12:44 .
drwxrwxr-x 8558 user1     user1     2494464 Jul  1 16:28 ..
-rw-rw-r--    1 user2     user2     23718 Jul  1 15:02 z6B00001-1593640926.readings
-rw-rw-r--    1 user2     user2     73606 Jul  2 12:44 z6B00001-1593719061.readings
-rw-rw-r--    1 user2     user2     232629 Jul  2 14:44 z6B00001-1593719062.readings

# showing current user
$ whoami
user1

# groups for current user
$ groups user1
user1 user2

# groups for user2
$ groups user2
user2 user1

# start python as user2
$ sudo -u user2 python
>>> open("/home/user1/filestore/z6B00001-1593640926.readings","rb") as f:
...     f.read()
Traceback (most recent call last): #<<< what??????????
  File "<stdin>", line 1, in <module>
IOError: [Errno 13] Permission denied: '/home/user1/filestore/z6B00001-1593719062.readings'
>>> os.system("whoami")
user2
0
>>> os.system("groups")
user2 user1
0
>>> os.system("ls -la /home/user1/filestore")
ls: cannot access '/home/user1/filestore/.': Permission denied
ls: cannot access '/home/user1/filestore/..': Permission denied
ls: cannot access '/home/user1/filestore/z6B00001-1593640926.readings': Permission denied
ls: cannot access '/home/user1/filestore/z6B00001-1593719061.readings': Permission denied
ls: cannot access '/home/user1/filestore/z6B00001-1593719062.readings': Permission denied
total 0
d????????? ? ? ? ?            ? .
d????????? ? ? ? ?            ? ..
-????????? ? ? ? ?            ? z6B00001-1593640926.readings
-????????? ? ? ? ?            ? z6B00001-1593719061.readings
-????????? ? ? ? ?            ? z6B00001-1593719062.readings
256

>>> exit()

$ sudo -u user1 python
>>> open("/home/user1/filestore/z6B00001-1593640926.readings","rb") as f:
...     f.read()
Traceback (most recent call last): #<<< what??????????
  File "<stdin>", line 1, in <module>
IOError: [Errno 13] Permission denied: '/home/user1/filestore/z6B00001-1593719062.readings'
>>> os.system("whoami")
user1
0
>>> os.system("groups")
user1 user2
0

expected behaviour is to be able to open and read(and write) these files as either user1 or user2... currently neither works:(

Answer 1

I feel extra silly... apparently the directory needs the execute bit set , and I had no idea

resolved with chmod 775 /home/user1/filestore

sorry i posted a question and then answered it myself... but im going to leave it since i didnt see a dupe in my 2 minutes of searching:P feel free to point to a dupe and close if such a dupe exists, or put a more thorough answer than this