What about my Johnny decimal level is alphabetical

Easy! Just assign numbers to things, in the order that you create them, and put them after the item.

So you keep your structure alphabetical and still get to assign a number.

Eighth thing you create [00.08]
Fifth thing you create [00.05]
First thing you create [00.01]
Fourth thing you create [00.04]
Ninth thing you create [00.09]
Second thing you create [00.02]
Seventh thing you create [00.07]
Sixth thing you create [00.06]
Third thing you create [00.03]
…and so on

(I like putting the numbers in [brackets] because I think it makes them more searchable, and it makes it clear in my mind that they’re not part of the folder name, but this is totally optional.)