This seems to work for me:
LANG=C grep --only-matching --byte-offset --binary --text --perl-regexp "<\x-hex pattern>" <file>
short form:
LANG=C grep -obUaP "<\x-hex pattern>" <file>
Example:
LANG=C grep -obUaP "\x01\x02" /bin/grep
Output (cygwin binary):
153: <\x01\x02>
33210: <\x01\x02>
53453: <\x01\x02>
So you can grep this again to extract offsets. But don’t forget to use binary mode again.
Note: LANG=C
is needed to avoid utf8 encoding issues.