If you can count your number of engineers on one or two hands, don’t worry about what agile framework is going to work best for you.
Instead, you should channel as much pg kool-aid as possible and just talk to customers. Figure out a way to consistently line up calls with your users. If you’re worried about needing to have a roadmap in hand, tell them what you’re working on and what you think you’ll work on next. See how they react.
But focus a lot more of your time on what you’re building right now, today. Tell them what you just shipped. Ask them to use it and give you feedback.
Take this feedback and use it to make your product better. That’s it. That’s agile.
Don’t worry about spinning up the massive overhead associated with SCRUM. Refrain from wasting time and authoring massive technical specifications or requirements docs for the one engineer to read. There’s a time and a place for that, but it isn’t here. Leave your playing cards in your desk drawer and don’t worry about pointing things. You’re almost certainly going to be wrong at this stage. Don’t worry about having a set sprint duration or figuring out how to see your burndown chart in Jira. Just focus on talking to your customers/users and shipping code, “working software”.
And when you talk to your users frequently, they’ll probably point out your mistakes or when you’re about to do something wrong. You’ll course correct mid-flight, because that’s agility.