This doesn’t aim to entirely replace find and ls, but if you already know SQL (like many of us do), why not be able to leverage that knowledge for your more advanced file-finding needs? Here’s a couple of examples so you get the idea:

Find temporary or config files (full path and size):

fselect size, path from /home/user where name = '*.cfg' or name = '*.tmp'

Use aggregate functions:

fselect "MIN(size), MAX(size), AVG(size), SUM(size), COUNT(*) from /home/user/Downloads"

Find by date and time intervals:

fselect path from /home/user where modified gte 2017-05-01