You can't use money without numeracy. Sure, just add the option of a decimal version with spaces between groups of 3 numbers, problem solved. Hexadecimal is only 5 more symbols than numbers. Illiterate people often do have basic phonetics and alphabet.

And maybe the bitcoin will give them some more spare time to learn to read better.

Seed phrases are anyway just 11 bit values, two base32 ciphers is the same as one word. Yes, in case you didn't know, a 12 word cipher only gives you 132 bits, it has to be hashed to get your secret. You could make a base32 equivalent of a 12 word cipher with 24 letter/number symbols like the Bech32 cipher set.

abcdefghijklmnopqrstuvwx

or as a decimal number, the maximum value for a 128 bit key seed:

5444517870735015415413993718908291383296

put spaces on it:

5 444 517 870 735 015 415 413 993 718 908 291 383 296

Still shorter! And I only need to be able to decipher 10 symbols.