Would like to try packaging software

If the upstream resides in git, it's really easy to use git based packaging: https://wiki.debian.org/PackagingWithGit/

https://optimizedbyotto.com/post/debian-packaging-from-git/

Essentially you just need to:

1. Build the correct directory structure within a subdirectory (e.g ./package/usr/bin for binaries, ./package/usr/share for docs, etc). This needs to include a few Debian-specific files, like a control file that contains metadata for the package, a copyright file, install and uninstall scripts if needed, etc.
2. Use dpkg-deb to package the files into a .deb file.
3. Run lintian to check that there's no issues with the package.

There's probably newer tools, but these are the core ones that have been part of Debian forever (and thus are very well-documented online).

You can then use Aptly to create a custom repo, or deb-get to install packages from Github releases.

I worked on the Debian packaging for Yarn v1. You can see the script that creates deb and rpm packages here: https://github.com/yarnpkg/yarn/blob/master/scripts/build-deb.sh (this uses fpm to build the rpm package, and the native Debian tools to build the deb package)

One thing I don't have experience with is submitting packages to the official Debian repo, so I can't help with that.

You will find some resources about packaging in the debian Mentors Faq., including about the intent to package (ITP) process.

More than a year years ago, somebody requested yazi to be packaged, and changed it to a ITP, but the bug is open (i. e. It has not been packaged or added). May be the first step should be send a email to the bug asking for the status of the bug.

Also, about packaging rust programs, you should check the documentation of the debian rust team packagers.

I would love to see yazi in Debian!

Well, that's a bit off topic, but may I ask why you want to do that? I can't imagine a scenario (for me as a single user) that would exceed the scope of checkinstall.