Hertzlich willkommen to the forum Heinzelmann.
Most dashcams are actually pretty small but often confuse people on sales pictures.
If your car have a shade / dot area on top of the windscreen, wedge shaped cameras are good as you can mount on that area and only have the bottom part with the lens peek out below that.
But these wedge cameras also often come off as just another sensor on the windscreen when installed at the top or beside other sensors already there.
One of the smaller 1 channel cameras are the Viofo A119 mini, there are also the Viofo A119 V3 but it is slightly larger.
Once the camera are set up you barely need to use the app or interact with the camera, but it is advised you format the memory card in the camera every few months, to reset the file allocation table, that can get fragmented by the many files getting made and deleted all the time.
The viofo app are just fine, even if some hate on it on user reviews on amazon ASO
I also use the APP on my phone s i have tired old eyes so the very small LCD displays on the cameras are very hard to read without reading glasses.
If you want to DL footage to the phone the A119 mini i think have a lot faster wifi than the "older" A119 V3,,,,,, but i am not quite sure here, but in the old days it could some times take 4-5 minutes to DL a 3 minute file, but on new fast wifi cameras we are talking under a minute to DL 3 minute of video to the phone on 5 GHZ wifi
Most cameras you can choose to record in 1-2-3-5-10 minute video segments, i personally use 3 minutes, if you want to compile a long video, just drop XX 3 minutte files into any video editing software, and they should be handled in the correct order in relation to the time / date name of the individual files.
It should take very few clicks by a mouse button and you have a new video that are 3 hours long or however long depending on the number and size of smaller clips you have used.
You should buy a large memory card, in general i advise at least 128 GB card for each camera, but actually i do mainly use 256 GB cards myself, you have to be careful with some brands of cameras in what memory cards they like, but they most often have a list of recommended cards on their home page.
In regard to night footage, any dashcam will always capture how you drive in relation to the side of the road and / or lane markings, it will also capture the light of intersections you go thru.
But capture of small things like a licenceplate that drive past you are very hard on any camera, but if the difference in the speed between your car and the other car are small, there are a good chance, same with parked cars, though mind you you have to drive slow, slower than you can drive on a bicycle.
Night time challenge are there for all cameras as no one use a super good secret image sensor, they pretty much all use the same sensors, and it is not like any of them are partikular better programmed from the factory to make a bigf difference.
The latest 4K cameras ( just one out atm ) use the Sony starvis 2 sensors named IMX 678, but so far its just the Viofo A139 PRO that use that sensor, but you can get that model in both 1-2-3 channel versions.
It is very new came out in december last year, it is also not as good as we hard core people think it can get, so there will probably be some improvements with firmware in the months to come, but on the basic operastion ASO it should work fine.
There are a sub forum just for the A139 PRO where you can find talks about it and video from it, i was sadly not given one of these to test so i can not be a part of that.