You can also submit a Flow as a template to template Gallery. Once approved it will be visible for everybody to use. What you need is a descriptive name and good description about it.
You can submit Flow created from Blank or a modified one created from template. Note that Microsoft may modify your template before it gets published.
To submit first you need to create a Flow first, you can learn how to do it from this post Microsoft Flow – Create from blank . Once done select “Done” and then you will see option to Submit to gallery.
Once clicked you need enter good description and submit it. If Microsoft think it’s worthy enough they will make it available.