I don’t know if this qualifies as “more elegant” but it is written in a different manner than Cybernate’s solution (although it is essentially the same)
WITH window_table AS ( SELECT s.*, sum(volume) OVER previous_rows as total FROM stuff s WINDOW previous_rows as (ORDER BY priority desc ROWS between UNBOUNDED PRECEDING and CURRENT ROW) ) SELECT * FROM window_table WHERE total < 1000 ORDER BY priority DESC
If by “more elegant” you mean something that avoids the sub-select, then the answer is “no”