Asymmetrical Armature Pose on Object with Mirror Modifier

I have an object with mirror modifier on the x axis and an armature consisting of properly named/parented bones for each side (ie: .R and .L on all bones accordingly). My problem is that when I connect the armature to the mirrored object it still affects both sides when posing.

I’m assuming it can be done, I seen a few people online discuss it, but following their techniques it doesn’t seem to work for me. In case it matters at all I am on Blender 2.9 with rigify enabled.

Applying the mirror modifier first and then connecting the armature and object works how I want, albeit without the mirror. What I am trying:

• Create armature with left side bones and right side bones (named with .R and .L using auto naming)
• Apply the mirror
• Bind armature to object with automatic weights
• Edit the object and delete half of it on x
• Add new mirror modifier on x axis
• Move mirror above armature

That doesn’t work, it seems that the unmirrored side still affects both sides and the mirrored sides weights aren’t connected to the mesh anymore.

What am I missing? I spent many hours trying to figure this out and I am getting really frustrated.

Here is my blend file with the object and arm before applying anything.
https://drive.google.com/file/d/1M4_KewAkS0WfTxRA7cOmBzCGpfYIktT1/view?usp=sharing