The Lasfit floor mats seem nice. I previously had the 3D mats and liked them, and I had some concerns that the Lasfit mats would move around without the Spider backing. However they are formed and fit very snugly so there really isn't any possibility for them to shift. They seem to be the same thickness as the 3D mats and should be as durable, and the Lasfits are a bit more rubberized so stuff doesn't slide around as much in the trunk.
I put a Spigen screen protector only on the rear screen, and so far so good. No phantom touches or real loss of precision. It's really to protect the rear screen from passenger damage, as I have younger nieces with legs just long enough to kick the screen. I had a front screen protector on my 2018 M3LR, and never felt it was necessary to protect the screen in front, so I won't be installing one this time. It's high enough that nothing really bumps into it accidentally.
And perhaps most controversially, I just added
BestEVMod's mud flaps. These are the kind that are formed and slightly wrap around the sides. I had Basnor flaps on my older car, and never noticed any paint wear on the wheel wells after 5 winter seasons, but also never really removed them. This time however the BestEVMod flaps come with PPF strips to protect the contact area paint. Seemed reasonable so I used them, just dry fit the flaps, block off with painter's tape, and use slip/tack solution to get the PPF strips placed.
I didn't like the profile of the Rally Armor flaps that seemed too floppy, so I liked these a bit better. We'll see!