I would echo the "I wish the split hadn't happened" voices but I suspect that the magic number of variants of an OS are around 3-5 and thats kind-of where we sit.

It always was (to some extend) a set: Bell vs Berkely vs Digital vs Sun vs "the rest" with things taken from each, and added back. Getopt, NFS, mods to the TCP/IP stack, ideas about virtual disks and filestores.

I may misunderstand, but I think there are "more" variants of Linux, but probably close to this magic number of really significant distros.

I drove FreeBSD as a desktop on multiple machines for decades. I now live in OSX but I continue to operate FreeBSD for research nodes on Dell, but with more debian in the mix now than before.

I'd love to try FreeBSD on RPi4 but what i read suggests it still has some issues in the uBoot and install area. I drive a 4 disk ZFS node through a jmicron USB-SATA bridge card, I need to be sure that will work before I can move but having adopted ZFS on Ubuntu the good thing is, ZFS variants apart, I SHOULD be able to do this transition without dataloss, assuming the controller chip works.

Up in server land I've migrated between Debian and FreeBSD for ZFS filestores multiple times. Its really easy.