ffprobe: how do I get the time zone of creation date?

[Posted on StackOverflow, then I realized that this is a better place for it]

I have a video made with a canon camera (actually a PowerShow G5Xm2), which was shot at 2022:08:28 11:25:09-04:00.

I want to extract the creation date metadata, and I found that I can see it with:

$ ffprobe -i myfile.MP4 -show_entries stream_tags
[.....]
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'myfile.MP4':
  Metadata:
    major_brand     : mp42
    minor_version   : 1
    compatible_brands: mp42avc1CAEP
    make            : 
    make-eng        : 
    model           : 
    model-eng       : 
    creation_time   : 2022-08-28T15:25:09.000000Z
  Duration: 00:00:53.96, start: 0.000000, bitrate: 29939 kb/s
  Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuvj420p(pc, bt709), 1920x1080, 29639 kb/s, 25 fps, 25 tbr, 25k tbn, 50k tbc (default)
    Metadata:
      creation_time   : 2022-08-28T15:25:09.000000Z
      vendor_id       : [0][0][0][0]
  Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 253 kb/s (default)
    Metadata:
      creation_time   : 2022-08-28T15:25:09.000000Z
      vendor_id       : [0][0][0][0]
[STREAM]
TAG:creation_time=2022-08-28T15:25:09.000000Z
TAG:language=eng
TAG:vendor_id=[0][0][0][0]
[/STREAM]
[STREAM]
TAG:creation_time=2022-08-28T15:25:09.000000Z
TAG:language=eng
TAG:vendor_id=[0][0][0][0]
[/STREAM]

The creation date in in UTC (2022-08-28T15:25:09.000000Z), and it has the format %Y-%m-%dT%H:%M:%S.%fZ. The camera has the info of the time zone, and actually it converted the local time to UTC time, so I suppose that the MP4 should hide somewhere the time zone info.

How do I see it?

exiftool has the ability to show date/times in local+tz format (like 2022:08:28 11:25:09-04:00) using the -API QuickTimeUTC flag. This means that tz info is in somewhere the mp4. How do I get the tz info with ffprobe?