Here's my attempt to answer these questions:
Nostr is multiple apps and platforms that interoperate together. There are Twitter-like apps, Reddit-like apps and there will be any kind of app you can imagine.
The developer team of each individual Nostr app controls that specific app. You can take control of the content you create but if you choose not to, the data is stored on someone else's devices. Often volunteers who want Nostr to grow and succeed in creating a better internet that is not controlled by a few big corporations. You can be blocked by individual users but you cannot get deplatformed from Nostr. Ever.
Each Nostr app has a way to create a Nostr identity. Once you have created one, you can copy your secret key that was created for you to a login on a different Nostr app. You can modify your profile name of your Nostr identity on any profile page on any Nostr app. Creating a Nostr identity doesn't require you to provide any personal information and you won't be required to do so ever in the future.
nostr:nevent1qqs2drkmn4tnadlepxfctkz49jpgl5p0th9xaw04ju5dwppfje9we0cpz4mhxue69uhkummnw3ezummcw3ezuer9wchsyg8pwfelhtfc0afwpjqs9h8u3kp3pet2lw854388v5l93jx4lz4lzgpsgqqqqqqs63qw59
What is the reddit-type app called?
Good question 😂 Don't trust, verify. The r/nostr community seems to suggest Amethyst, Damus, Primal and Snort to new users so I guess the Reddit-style client hasn't released yet. The point is to emphasize that Nostr isn't limited to just one use case.
Should probably say Twitch-like platform or a food recipe app instead of reddit to get the point across better.
Nicely done! It is worth thinking about this, and revisiting it often as we think of how to explain Nostr, especially as the authoritarians of the world increasingly try to lock out the centralized SM apps. If we make it too confusing for people, it will slow down adoption.
There's a reason why the majority of brazilian X users went to Bluesky instead of Nostr.
Para os brasileiros eu recomendo usarem o Amethys, pois ele traduz as postagem.
---
For Brazilians I recommend using Amethys, as it translates the posts.