Is this card fast enough for 4K video?

The listing rates reads up to 200MB/s and Class 10, which covers basic video capture. It does not state a write speed or V30 rating, so check the write figure before relying on it for high-bitrate 4K.

How is it different from a UHS-II card?

It uses the UHS-I interface, so it tops out well below UHS-II cards in devices that support the faster bus. In UHS-I devices the two perform similarly.

Will it work in a Nintendo Switch?

Yes. The Switch uses microSDXC cards, and 512GB gives room for a large game library. No A2 app-performance rating is listed, so load times are typical rather than optimized.

Does it come with an SD adapter?

The listing does not confirm an adapter in the box. If you need to use it in a full-size SD slot, verify the package contents first.

Is 512GB the right capacity?

It suits people storing hours of 4K footage or dozens of large games. If you mostly shoot photos or short clips, a smaller card in the same line is simpler to manage.