I dont actually understand the instant exchange part so if you can elaborate.
That is quite interesting part and I would like to elaborate on that in a more detail.
If I understand this project well, we can exchange tokens of the network and also other blockchains instantly
Actually you can only exchange the tokens that is issued inside the minter blockchain. Tokens on other blockchains are not supported. At least for now. The team where saying that they wish to integrate BTC and ETH in to the blockhain in their official telegram but with no ETA's.
Who are the people going to be buying that instantly?
The tokens one may want buy and sell are not from other traders like on other dex'es but from the system itself. Emission of every token is "limitless" (that's what is PSO is stated for), actually the only limit is the price of the custom token. After each buy and sell price of a token get changed by the system. If a price or number of tokens in a circulation get's too low the token gets liquidated. And if it is useful the price goes up eventually.