Many ways to do this. First, is this the main panel? If so, SEU is the wire needed. Two hots And a ground.
If you have a meter main, or breaker outside, then the panel is a sub-panel and you need 4 wire ser. I don't see why you can not nipple through meter into panel. And remove the short studs in the way. Use pvc as it's a little easier to work with.
SEU is allowed and is done all the time without conduit. Just have to watch length of wire. And you could sleeve it to protect or not.
Make sure you bond the panel if a main, which should come with bond screw, or you have to get ground bar to add to panel and not bond panel. White or neutral to bar on panel. Bare grounds to added ground bar. Also check the ground rods . and wire to them.
If this the main panel run water bond to it. If sub-panel water bond goes to meter main outside.Cover hole bay with plywood, screw on so easy to add wires later. And mark the ground wire, green tape or bare. By doing this you do not have to run cable in conduit. Only were they are open in the garage which should be done where they come down to outlets or switches. Up high on joist is ok as long as nothing stored up there.
