Lots and lots of best practice exists specifically to help
teams, and especially teams with some normal amount of turnover.
The problems of a solo dev are very different than a dev on a team. Knowledge silos don't exist. Distributed expertise doesn't exist. There's no one to mentor, no shared vision to maintain, no intertia to combat.
I consult on big complicated team projects. I also manage multiple solo projects.
On solo projects, deployment is a script I run from my dev machine. I'm the only person who deploys; anything else would be solving a problem I don't have.
The only "CI" is running the tests before I run the deployment script. I'm the only one who needs to see the outcome of the tests. Anything more would be solving a problem I don't have.
Architecture is whatever makes the most sense to me personally -- which is often miles away from what I would recommend to a client, who needs something any new hire will recognize and be able to work with.
I pay a service to manage backups so I can walk away from a solo project for months and know it's ticking away.
The point is: solve problems you actually have. Don't try to run a "professional" operation by doing what big teams do all by yourself. Big teams have different problems.