1- Hosting site on one of the service providers doesn't mean centralization, ex. these week amazon outage, if you are going to deploy to multi-providers it will costs much, in our solution we offer you freedom of hosting on whatever relays you prefer many relays are public which means 0$ cost, moreover you able to expand your deployment on more relays as you want.

2- You are definitely correct, We have just highlighted a small note in the landing page that end users need extension to access the website, to gain some trust we have published the extension to chrome and Firefox store so a code review is applied to ensure security.

Really appreciate your feedback we can add more informative details in the landing page to show why end user need an extension, also we are planning to build a gateway so end user doesn't need to install extension in order to to access nostr websites "Frankly speaking we don't prefer this way in favor of decentralization and it is planned just for demonstration purposes"