Do you use FE framework or stay with serverside rendering when building MVP?

I agree with the main thrust that you should just do server rendering if you can, but I've gotta say, the options presented are decidedly suboptimal.

If it's appropriate for your project, you'll move faster with an MVC server-side project. The fastest option would be Rails, while Laravel and Phoenix would be the next quickest options (and do better with hardware efficiency). Django is kind of the worst of both worlds—not quite as fast for development and the worst performance of any. The exception would be if your MVP includes a lot of ML/NLP/etc, for which Python's library support is top notch.

If you MUST use a FE framework, then go with something like Vue, not React. The goal is to get to market ASAP. React has more job openings, is much more popular (and arguably better) for large-scale apps, but that doesn't matter for a start-up. Similarly a complex containerization-based infrastructure is great for Google, but probably not for levelsio or you.

Also, rather than aiming for "as boring as possible", go for "as productive as possible". Over half of the market cap of all YC companies is from companies that started with Ruby on the back-end. A few of them, like Podia and Coinbase were started when that was already a boring choice, but it sure wasn't a boring choice when Airbnb, Twitch or even Stripe picked it. It was a competitive advantage.

Had they gone with "boring" Java of the mid aughts, there's a good chance they wouldn't have gotten to market fast enough.

React is becoming so strong !