3. Burned the DVD iso with Xorriso and real tested DVD discs in standalone players

Re-encoded and muxed first first a full scale DVD video base file, DV01-1992.mpg 3.9 GB (53 min playtime) with FFmpeg as step 1 above.
During this proces the previous "buffer underflow" messages scrolled over the screen. However the mpg file fullfilled , without knowing if the messages caused issues.

Loaded it in DevedeNG which generated the DVD tree structure and iso as step 2 above (in a couple of minutes)

3.1 Burned the DVD-01_1992.iso file afterwards with Xorriso (K3b default from DevedeNG GUI)
Tested two disc types, DVD+RW and DVD+R

xorriso -as cdrecord -v -sao dev=/dev/sr1 DVD-01_1992.iso


3.2 Both DVD Video+PCM discs loaded automatic the DVD-disc logo&file name in a newer Samsung UHD BD-player.
The playback started ok with the play key and displayed correctly 4:3 aspect ratio. Jumped worked between chapters.

Tested also the discs in an old Toshiba DVD player, which loaded and stretched horizontally the 4:3 image and video to 16:9 width.
Tried several menu setup steps with 4:3 included, but still stretched image. Seems like it didn't recognize the SAR/DAR on the disc.
Both players were connected via HDMI to a 16:9 PC monitor (Asus). Possibly a TV monitor could force the image to 4:3 scale width.

Both player's setup menu confirmed PCM audio.