Just use Postgres

Postgres should always be your first database.

Always.¹

It covers a wide range of features is mature, reliable, fast, extensible, and boring in the best possible way. And you can use it in virtually any language.

I find its breadth of features especially useful when still figuring out the design of a system. It’s much easier and faster to iterate by using different set of features or a different structure of the smae database, than it is to swap it for another one entirely.

And if a bottleneck is ever reached, it should be obvious why - and you should be left with few obvious options.

Until then, just use Postgres.