I am able to update the TinyTV software using a Mac (M2 Mac Mini running MacOS Tahoe 26.6.2) but there are some undocumented limitations.
1) If you use a VPN it must be turned off or disconnected. The update process is not compatible Proton VPN.
2) The update process is not compatible with all browsers. It does not work with Firefox but it does work Google Chrome  .
3) I used a USB-C connection via a powered hub connected to the Mac Mini's USB-4 port.
4) You have to use the manual process (that involves using the reset button on the bottom of the TinyTV.

Hope this helps someone

[sort of]

Using Version 1.2.0 of the TinyTVConverter App and a TinyTV2 with software updated to version 1.30. I can get the MP4 video files to work "sort of". It is really nice   that the converted MP4 video files are more the 10X smaller than the corresponding AVI files with no apparent degradation to video quality but there are some bugs   in the MP4 files. First, they only playback correctly when the playback starts at the beginning of the file. If the playback starts any place else, there is no sound (this is true with both with playback using the TinyTV2 and a video player [VLC] on the computer).  In addition, on the TinyTV2, the MP4 video files will only play consecutively or in file order. If you try to turn the "channel" selector backwards, the TinyTV2 freezes. So in other words, MP4 playback on the TinyTV2 only works if you, configure the TinyTV2 to play the files from the beginning of each file, and you either allow the video to loop, play sequentially or only change channels in the forward directions.   These issue do NOT exist if the video files are in AVI format