Hmm, probably nothing, and I think that would be broken on mobile. If there was an add-on that auto updated the deck name numbers, that would be useful.
One way that I cheat is by using Greek letters that look identical to Latin letters. If you have a deck “Portuguese” and for some reason want it to show up after “Zulu”, you can use a capital Greek rho for the first letter, “Ρortuguese”, and it will go to the bottom of the list. But this has its drawbacks, and obviously only works for a few letters (capital alpha, beta, zeta, omicron, rho, …).
Edit:
For capital letters, you can cheat with (at least) the following:
Greek
Α Β Ε Η Ι Κ Μ Ν Ο Ρ Τ Χ Υ Ζ
Cyrillic
А В С Е Н I Ј К М О Р Ѕ Т Х
(I include Cyrillic К even though it doesn’t look exactly like K.)