You can build your own LTS image relatively easy and free of charge
And I have been unable to build a cloud-init image.
But the ISO is buildable from the LTS branch and it works well.
I'm usually all for up to date software, but on my networking equipment??? I don't really want to beta test that stuff, but that's what they seem to want to make me do.
You can build the ISO from the LTS branch though and that branch doesn't move much. Though, I don't know how you can tell which commit was used to release, say v1.3.2. For the moment, I simply build an LTS ISO using the latest commit of the LTS branch. That strategy has been rock solid for years now.