@hi I just run "sshd -p 4242", and then can login via

"ssh foobar@<ip-adderss> -p 4242", where "foobar" is the account name - probably set up by termux automatically, You can see it by typing "whoami".
You'd also need to set up a password for "foobar" (or add an ssh-key - I didn't try this)