In some way yes, but Docker is containerization engine, which can be used to selfhost stuff. Yunohost is special OS for selfhosting and only selfhosting. Apps installed using Yunohost are not containerized, and they are made for easy deployment.
Yunohost provides free domains (nohost.me, ynh.fr or noho.st) with Dynamic DNS, but i bought domain in Gandi. I use this simple script https://github.com/cichy1173/yunoDnsUpdater to update DNS if IP changes. I am thinking about buying fixed IP, but it is additional cost every month.