I have now downloaded several sample videos for some of the more recent cameras.
Then I have analyzed them with exiftool directly and later in IMatch what metadata is available in videos.
I've put this together in an excel file (see also attached file).
This is sorted from new to old. As you can see all recent cameras I tested (2015 or newer) use the QuickTime tags (marked in green) - with the exception for Olympus and bitrate tag.
Camera Model and Lens is still a mess.
Older Cameras (2009-2014) were using M2TS tags (blue), and very old ones (<2009) RIFF tags (yellow).

Since my newer cameras are all Olympus and the rest is older I'm missing a lot information in the QuickTime tags.
I have now created a layout that uses all the tags I found:

For the Sony A7SIII sample file I downloaded it seems like date was set wrong, and also has forgotten to set the {File.MD.XMP::XML\DeviceModelName\DeviceModelName\0} tag corretly (set to: MODEL-NAME)
Input used:
Camera: {File.MD.Olympus::prms\44\Model\0}{File.MD.Exif::Main\272\Model\0}{File.MD.H264::MDPM\228\Model\0}{File.MD.XMP::XML\DeviceModelName\DeviceModelName\0}{File.MD.QuickTime::ItemList\model\Model\0}
Lens: {File.MD.photools.com::IMatch\2900\lens\0}
fps: {File.MD.QuickTime::SampleTable\stts\VideoFrameRate\0}{File.MD.RIFF::StreamHeader\5\VideoFrameRate\1}fps
Bitrate: {File.MD.Composite\QuickTime-AvgBitrate\AvgBitrate\0}{File.MD.RIFF::AVIHeader\1\MaxDataRate\0}
Video Codec: {File.MD.QuickTime::ImageDesc\2\CompressorID\0|replace:avc1==h264;replace:hvc1==h265}{File.MD.M2TS::Main\VideoStreamType\VideoStreamType\0|replace:H.264 (AVC) Video==h264;replace:H.264 Video==h264}{File.MD.RIFF::StreamHeader\1\VideoCodec\1}
Audio Codec: {File.MD.QuickTime::AudioSampleDesc\4\AudioFormat\0|replace:mp4a==AAC (Advanced Audio Coding);replace:raw==PCM unsigned 8-bit;replace:twos==PCM signed 16-bit big-endian;replace:sowt==PCM signed 16-bit little-endian;replace:lpcm==PCM signed 24-bit little-endian}{File.MD.M2TS::Main\AudioStreamType\AudioStreamType\0}{File.MD.RIFF::AudioFormat\0\Encoding\0}
Audio SampleRate: {File.MD.QuickTime::AudioSampleDesc\32\AudioSampleRate\0}
For VideoCodec I do the following replacement:
hvc1=h265
avc1=h264
For AudioCodec I do the following replacement:
mp4a = AAC (Advanced Audio Coding)
raw = PCM unsigned 8-bit
twos = PCM signed 16-bit big-endian
sowt = PCM signed 16-bit little-endian (twos spelled backwards)
lpcm = PCM signed 24-bit little-endian
My conclusion is:
For newer models (2015+, also applies to mobile phones) one should be pretty save with the quicktime tags (with exception of Olympus and bitrate)
The cmd script I posted earlier in this post is listing all the informations corretly for all cameras I tested (e.g. also bitrate for Olympus and older Panasonic models)
I will now work with some layout as shown above for videos. Manually I will only assign the camera-name to tag {File.MD.XMP::xmpDM\cameraModel\CameraModel\0} -> so I can work on categories on this one...