Document the functional process
When I create a new project and want to deploy it I always start to right down the manual steps in a README, but one could also create a txt file or sheet like you did.
Feel the pain
At a certain moment when I have deployed the project manually the pain of certain steps will become clear. For example, I add per step how much time it takes.
Automate the high ROI steps
If for example a certain step takes half an hour an one deploys twice a week, one could investigate how long it will take if one automates this step (investment) and what time it will save (return). One could decide to create issue tickets and automate steps every sprint.
Example deployment plan
For one of my current projects I have to deploy multiple microservices. I will not provide all details, but initially the plan was two pages long. Now I only use a Continuous Integration/Deployment (CI/CD) plan and a lot of abstractions. If the deployment will fail some day I could still read the initial plan so that the functional flow is still clear.
Configuration as Code
Another benefit of automating the manual step is that one could save the code in a Git repository as a pipeline script. When another person reads the scripts then it becomes clear how the project is deployed and one could also trace who made some change, what modifications were done and when.