DV import to Sonoma still works
FYI: DV import still seems to work with macOS 14.2.1 Sonoma.
I did a quick test by connecting Sony TRV320E D8 camcorder to 4-9 pin FW cable to Apple's FW-TB adapter to Apple's TB2-TB3 adapter to Intel Mac mini 2018 USB-C port, macOS 14.2.1.
System Information > FireWire and Thunderbolt/USB4 (Bus 1) show the camcorder and the Firewire adapter.
Initially QuickTime Player or Final Cut Pro 10.7 did not show the camcorder but after this they do:
Final Cut Pro 10.7 imports 720x576 as 25 fps bottom field first interlaced, overall 30.5 Mb/s, timecode .mov (DV, 16 bit 48.0 kHz 1536 kb/s PCM Little / Signed) from that PAL camcorder (4:3). My old .dv files archived from iMovie 1.0.2-6.0.3 are essentially the same except .dv, overall 28.8 Mb/s, no timecode and PCM Big / Signed.
So I'd recommend FCP import for the quality I am used to, although that must be deinterlaced for computer playback unless longer shutterspeed was used making the footage essentially progressive.
On the other hand, QuickTime Player.app "Maximum" setting imports 702x576 25 fps, overall 40.3 Mb/s, timecode .mov, ProRes 422, 16 bit 48.0 kHz 1536 kb/s PCM Big / Signed, and "High" setting imports 585x480, overall 4351 kb/s, timecode .mov, AVC, 48.0 kHz 320 kb/s AAC, both as progressive.
A strange thing about those new Sonoma "legacy settings" was that enabling them made importing possible. But System Settings > Privacy & Security > Camera did not report the alert: "If legacy video support has been restored, you get a warning that the camera privacy indicator won't appear in the menu bar when a camera or video output device with an unsupported plugin is in use." And even after I changed back to the default settings, FCP and QuickTime Player still could import DV.
Mac mini