create or replace function utf8x(codepoint) as (
   select hex(encode(chr(codepoint)))
);

# Example:
select s,
       unicode(s) as codepoint,
       chr(codepoint) as c,
       unicode(c),
       utf8x(codepoint),
       decode(from_hex(utf8x(codepoint))) as "decode(from_hex())"
from values ('A'), ('ö'), ('Ж'), ('€'), ('𝄞') t(s);