In the kernel, the last commit in the IEEE 1394 area was a month or so ago—it's not 'active' maintenance, but its definitely being maintained, and is quite stable in my testing. (Thanks a ton to the current maintainer, who's going to go through the 3 year process of sunsetting full kernel support, and coordinating that with external projects!)
Every Apple device from the late 90s to 2012 had FireWire. Most Sony PCs from the late 90s to 2009. Google estimates that at over 100M systems with FireWire. There were 50M Zip drives, in comparison.
I know I should probably move on, but I have a lot of FireWire block devices and video equipment. The disk/disc drives can be moved to USB, but the video equipment cannot.
And floppy support is needed for cloud-init, heh.
[0]https://ntrs.nasa.gov/api/citations/20060009084/downloads/20...
https://github.com/torvalds/linux/commit/0d6dd4738dbcc32b60c...