Being issued on Stellar blockchain, PSH will automatically become tradable on the Stellar Decentralized Exchange (SDEX), hence, not necessarily required to be listed on any 3rd party crypto token exchanges (unlike e.g. ECR-20 tokens).
I think you entered the statement incorrectly here, You said unlike ERC-20 tokens? As I know, ERC-20 is an Ethereum tokens. Did you know that Ethereum is also have Decentralized Exchange? Even I thought their decentralized exchange is more than the stellar have. This will make a lot of people offended, because ERC-20 is the mostly used at this time.
Yes, obviously there are many exchanges, centralized and decentralized, that are listing ERC-20 tokens and many more than listing Stellar based tokens. However, as correctly stated, Stellar based tokens does not need to be listed on any 3rd party exchanges, since SDEX is in-built feature of Stellar blockchain (something that e.g. Ethereum blockchain does not have). We are not trying to say, that Stellar is better than Ethereum or vice versa, but just stating some of the unique features of Stellar blockchain and using ERC-20 as an example, since it is most widely used and known on Token Sales.