Any website that implements ActivityPub APIs properly can federate with other sites as part of the fediverse.
In the light of the above ☝️ statement and in the context of the given lemmy post, l am presenting three websites as an example :
Can such websites be created and made to federate as a part of the fediverse ?
I found these links particularly interesting 😃😃😃
https://fediverse.info/
https://joinfediverse.wiki/Main_Page
https://the-federation.info/