It’s amazing how much complexity one person can wrangle.
In a post - The Tech Stack of a One-Man SaaS:
treat infrastructure as cattle instead of pets
choose boring technology
Moved DigitalOcean to Linode because of stability issues. Then moved to AWS due to a good deal.
Migrations were relatively easy because the infrastructure was described via Terraform and Kubernetes manifests.
A Hackernews discussion shares similar experiences by other successful one-person SaaS founders.