SmartOS hypervisor can also run SmartOS vm's, which I have put to excellent use. Tend to give me much better bang for the buck, provisioning wise, than Linux vms.
Familiar with Alpine for a long while now. Used to use Void linux, wh/also has options for glibc and musl based fun and games. Hence, a fair bit of cross pollination 'twixt the Void and the Alpine devs when it comes to musl package tweaks and glitches. Mayhaps now infrequent, as I've not used either in years.
Speaking of Void linux, you may want to check it out if your main aim is to be systemd free. Void uses runit, which I personally prefer to Gentoo's OpenRC. Already grok OpenRC... have fun with Alpine. Keep us posted, as, as mentioned, was under consideration here but I lacked requisite time to kick the tires.
My $0.02 is this, that, and the other Linux flavor of the day pretty much boils down to package management, init systems and community. After those, cool "esoteric" stuff like musl come into play.