Focus on your business, open the smallest and simplest entity you can to validate your product before spending time and money optimizing or scaling things. That being said, I’m familiar with GmbHs in Germany and I would advise against going this route unless funding is available. Try a sole proprietorship instead if possible.
edit: just stumbled upon this really good blog post about the topic, in case anyone is interested: https://eidel.io/posts/estonias-e-residency-is-awesome-and-s...
The bureaucracy argument is real. Setting up an Estonian e-residency company is genuinely faster and simpler than a German GmbH. You can do it fully online, banking included if you use a provider like Wise or LHV.
But a few things nobody tells you upfront:
Banking is the friction point. Getting a proper business bank account as an e-resident is harder than it used to be. Most EU banks won't touch you without physical presence. Wise Business works but has limits. Factor this in before you commit.
Your tax situation doesn't change. This is the one people get wrong most often. You still pay taxes where you live. Estonia's 0% corporate tax on retained earnings is attractive but irrelevant if you're paying yourself a salary as a German resident. Talk to a tax advisor before assuming you'll save anything.
For a small SaaS it is probably worth it purely on the simplicity side. Less paperwork, easier to manage remotely, straightforward annual reporting. Just go in with realistic expectations on banking and taxes and you will be fine.