figlet -f banner 'foo' | sed 'y/# //'

(should work with `tr '# ' ''` too, but I only have the busybox version which only works with ASCII)

EDIT: and I forgot what a pain Unicode can be on HN as well. Unbutchered here: https://pastebin.com/jVSUwVCS

You could just send an actual image as an attachment.