samuraidan He's not, he's just being a programmer and general dev that doesn't appreciate how complicated pathfinding algorithms and other bits of work are because he looks at far more complex stuff every day and they always come across badly to noobs and others asking questions when they post like this LOL, I've caught them out and sometimes myself numerous times thinking like this. I might reach the point where I regard this type of thing as 'easy' but honestly I find working with 3D far better in Godot, the TileMaps seem to be a genuine pain for quite a few people, even the experienced ones.
It seems like TileMaps are being misinterpreted a lot as how to use them and I think that the Godot 4 documentation is partially to blame because it's not clear enough on what can be done and what can't plus the proper methods to do various mechanics like click to move with obstacles and I regard that as incomplete. I think he is right though, if you're really determined a custom A* algorithm is probably the way to go and that's the conclusion I've come to, I'd rather just switch to low poly 3D myself though because ironically the maths is now easier on that for me and I know what I'm trying to do will work. I've experimented heavily with 3D pathfinding and it's a lot better.
The problem is and I was thinking about this, the argument to be made on the opposite end is that really quite a lot of behaviour we expect from TileMaps like the navmesh for cells clearing when they have a NavmeshObstacle2D put over them should certainly be features in by default or have some easier way to access individual tiles without having to do a silly amount of code. At the very least back end devs come on, please let us have some kind of code to access the individual tiles in a less silly and hacky way than what I've had explained to me.
It might seem really odd, but I've been thinking, especially since you're doing a top down shooter I guarantee you it will probably be easier doing everything in 3D. In fact something really odd I was considering was the idea of using 3D sprites and a bit of optical illusion trickery to deal with all of the collision problems, that might also be worth a revisit. You would simply have to make sure the 3D sprites were facing the right way up for your top down camera among other things, this might even be a way of dealing with this problem if rather ridiculous, think Doom sprites but on a different axis.