Are they trully 100% random (generated by hardware) or is it pseudo-random (generated by software)?
They aren't random. They're a pure function of the data in the block. They are not (believed to be) predictable in advance, but miners can influence them by changing the data in the blocks to get different results. This is how mining works.
Can i rely on it or any other blockchain data to make a 100% trustable raffle?
The security of doing that is limited. If you entire raffle process is known in advance miners can cheat your raffle at some cost by throwing away otherwise valid blocks that would go a direction they don't like in your raffle.
There are ways to avoid this (e.g. first publishing a commitment to a secret which is combined in the selection) but really, to be frank, if you're asking very simple questions like this you likely have a long way to go before you're ready to design a cryptographic protocol for other people to use. You probably need to spend some more time reading.
