Unfortunately not, jmmv hasn't updated the script yet. A issue was created on gihtub, but no PR committed; personally I don't use sysupgrade, but if you do, you can consider submitting a PR yourself, remembering to cover both legacy and new compression format with a if statement, depending on uname -r. I look forward to things like
basepkg (new, currently available in pkgsrc/wip) getting upstreamed, even against syspkg project which I can figure has been stagnating for quite some time already