Solution: Gather until full

Here is a possible solution to the task.

Code

my $sum = 0;
my @result = gather for 1..100 {
    $sum += $_;
    last if $sum > 10;
    take $_;
}

say @result;

🦋 You can find the source code in the file gather-big.raku.

[1 2 3 4]

The loop is given a range of a hundred numbers, far more than it will use. That is fine because the loop stops itself: as soon as $sum passes 10, last breaks out and the remaining numbers are never visited.
The order inside the block matters. We add to $sum first and check the limit before taking, so the number that tips the total over 10 (here, 5) is not collected. The running total reaches exactly 10 after 4, so the gathered list is 1, 2, 3, 4.
This early exit with for is what gather/take can do and grep cannot: grep always scans the whole list, while here we choose when to stop.