If you're using pre-compiled images, OpenWRT has a package manager and repo with OpenSSH in it. I used to do something like this[1] to install and update OpenSSH outside of internal flash, before deciding that exposing SSH on my router was a bad idea in general.
If you're compiling OpenWRT yourself, you can easily just switch them out in your base image, too.
If you're compiling OpenWRT yourself, you can easily just switch them out in your base image, too.
[1] https://openwrt.org/docs/guide-user/additional-software/extr...