@AndrasNS :
Here are a few additional thoughts for your consideration.
1) Moving the unit.
I made provision, a year or so ago, for a Peak Design phone mount, with vibration dampener, for
very occasional use of my iPhone Pro 11 if I absolutely need directions from some GPS app. (On my Royal Enfield Meteor 350 I mounted a cheap Aoocci C6 CarPlay unit, as a fixed, i.e., "permanent" device on that bike.)
I mention this because you may find inspiration from that work. I used a bracket I found on AliExpress -- this was for my '23, but there may be something similar for your '25 -- along with some RAM products, and some theft-resistant couplers (this sort of thing:
https://www.amazon.com/FANAUE-Aluminum-Anti-Theft-Compatible-Motorcycle/dp/B0CPHPRH79/).
This is what that looks like:
In my C 400 GT gallery, I have a series of pictures and captions regarding this project, starting here:
https://billanddot.com/C400GT/#S-178
There are also some ready-made products for moving BMW's nav prep units from a British company called Moto Mate:
https://moto-mate.com/product-category/gps-mounts-phone-mounts/raised-gps-mounts/bmw-gps-mounts/
While I don't see anything specific for the C 400 -- no surprise there -- you might want to touch base with them. Possibly the unit for the F 800 GS --
https://moto-mate.com/shop/gps-moun...d-navigation-mount-adjustable-touring-screen/ -- could be adpated for the C 400.
So if the wire bundle that connects to the nav prep bracket has enough slack -- extra length -- to it, you might consider moving the bracket up higher, where I have my phone mount, using some combination of products.
2) Locking.
If I understand the information correctly, BMW has a locking device for the nav prep holder. See, for instance, here's a short video:
And also see
https://support.chigee.com/portal/en/kb/articles/aio-6-lock-on-bmw-quick-release-module and
https://www.bmwestore.com/oem-parts/bmw-motorrad-lock-navigation-preparation-65908524456.
However, given the expense of your Chigee unit, if I were stopping for lunch where I couldn't see the bike, or going into a mall, etc., I would dispense with any locks, and just remove the unit, which is easy enough.
I record all my rides with a GoPro up front. I have a quick-release mount (on both bikes), so I can just squeeze two tabs to remove or insert it. When I'm in those situations -- pretty much off the bike for any reason other than to get gas -- I just unsnap the camera, and lock it in the top case.
Similarly, although I used some theft-deterrent connectors for my PD phone mount, removing the phone itself from the mount is also a matter of just squeezing two tabs (and then putting the phone in my pocket).
Bottom line: if I had an expensive CarPlay device, I don't think I'd use a lock for it, but would instead lock it up when I left the bike.
(On the other hand, as I mentioned, on my Meteor I don't have a snap-in bracket, i.e., the entire system is all theft-deterrent connectors. But the difference is that my CarPlay unit is cheap, and also that bike is not suitable for multi-day trips, doesn't have much storage, and so forth, so I only ride it for day trips, park it in front of a diner or fast-food place where I can see it, don't take it to a mall or grocery store, etc.)
3) Videos.
As I mentioned earlier, I don't know of any bike forums that somehow let you upload videos. I just use my (free) YouTube account, put up a video there (recall my comment about my riding with a GoPro), and then put its link in a post.
If you want to see how that comes out -- in addition to the video that I linked to above -- that's what I did just a few days ago, for instance, here:
https://www.bmw-scooters.com/threads/c-400-gt-ny-to-ma-to-ct-to-ny-to-ma-to-ny.3731/
In any case, happy riding, and congrats again.
