I haven't done this myself, but I assume you can turn off the display in Desktop Mode. I assume somewhere in the "normal" Linux settings there will be the usual Turn Screen Off after ... and Go To Sleep after ... You could just set the screen to turn off after 5 mins, then set sleep to never and that should do it.
I significantly prefer it for car navigation, it seems to always pick 'more sensible' routes than Organic Maps. Also the live traffic is very nice to have.
I prefer Organic Maps when I'm on foot, ie. walking through the city or hiking. Imo it feels less cluttered when you just want to look at a map.
Edit: Another big plus for Magic Earth is transit support. It's not as good as Google Maps, but it's certainly better than nothing.
While not FOSS, the closest thing we have to a drop-in replacement would be Magic Earth. It uses openstreetmap data, supports fully offline usage, has satellite images (only online though) and best of all, no tracking or telemetry.
I assume the tablet gets its video through standard HDMI/DP over USB-C, hence a USB-A to C adapter wouldn't work.
If you still want to use the tablet with the official dock, there may be HDMI+USB -> USB-C adapters capable of inserting the HDMI signal into the USB-C connection. I'm not too knowledgeable on this topic, so you may want to resort to some more research of your own.
Also keep in mind (as far as I'm aware) there's a hard limit on 2 external monitors, unless you use some "trickery" like DisplayLink.
Edit: I've done a bit more research and I'm pretty sure that more than 2 monitors are supported. There are two limiting factors here:
The GPU in the Steamdeck (custom APU which I didn't directly find a spec sheet for), will typically have a max of 2-4 displays
The physical connection, AFAIK as the Steamdeck only has one USB-C port, this means it has one DisplayPort 1.4 link available. This link can be divided into multiple video streams. I couldn't find a table for DisplayPort 1.4, but this website has one for DisplayPort 1.2, suggesting you should be able to run four 1080p60 signals at the very minimum.
Now with all this information, as long as your Steamdeck can output to any three screens (ie. two external ones and the internal steamdeck screen), it should also be possible to output three 1080p60 signals to external monitors.
Hm there must be some other problem on your end then. Doing a clean reinstall of Yuzu EA 4176 and then using the newest keys, firmware and update for Mario Kart 8 Deluxe should pretty certainly fix it.
It runs great for me on Steamdeck, with the Yuzu EA 4176 AppImage, firmware/keys version 18.0.0, MK8 Deluxe NSP + Update 3.0.1 + DLC.
I just read the full article, and I'm not even that concerned about storing the key in plaintext. I find the possibility of copying the files, and then being able to run the same session simultaneously a lot scarier.
As the article states, currently all processes are able to read the file which contains the key. Instead, you could store the key in the macOS Keychain (and Linux/Windows equivalents), which AFAIK is a list of all sorts of sensitive data (think WiFi passwords etc.), encrypted with your user password. I believe the Keychain also only let's certain processes see certain entries, so the Signal Desktop App could see only its own encryption key, whereas for example iMessage would only see the iMessage encryption key.
The latest yuzu version has a bug with Mariokart multiplayer (I believe this is the one that you're referencing). It can easily be avoided by pressing L+R on the first screen with any controller that isn't Player 1.
I was never in a situation where I had to choose which fliphone to buy, but most don't have a normal headphone jack, with a decent number of them also using a fully proprietary headphone port. So I guess I'd look out for it having a normal USB connection and ideally a fullsize headphone jack, or at least one of those smaller diameter jacks.
I haven't done this myself, but I assume you can turn off the display in Desktop Mode. I assume somewhere in the "normal" Linux settings there will be the usual Turn Screen Off after ... and Go To Sleep after ... You could just set the screen to turn off after 5 mins, then set sleep to never and that should do it.