[@sheet]  Should @import be possible within @sheet at all, should it be allowed if it's the first/only statement, or should it be blocked?

Behavior of @import - should @import be possible within @sheet at all, should it be allowed if it's the first/only statement, or should it be blocked? There was discussion of this in the CSSWG, but no conclusion was reached. This was briefly discussed in this CSSWG conversation: https://lists.w3.org/Archives/Public/www-style/2023Apr/0004.html