This is possible, but it will require the use of a separate Nostr app called listr.lol by nostr:nprofile1qythwumn8ghj7un9d3shjtnswf5k6ctv9ehx2ap0qyvhwumn8ghj7un9d3shjtnndehhyapwwdhkx6tpdshsz9nhwden5te0wfjkccte9e4x2enxvuhxv7tf9uq3zamnwvaz7tmwdaehgu3wwa5kuef0qy88wumn8ghj7mn0wvhxcmmv9uq3samnwvaz7tmxd9k8getj9ehx7um5wgh8w6twv5hszxthwden5te0wpex2mtfw4kjuurjd9kkzmpwdejhgtcpzdmhxue69uhhqatjwpkx2urpvuhx2ue0qy2hwumn8ghj7un9d3shjtnyv9kh2uewd9hj7qg6waehxw309aex2mrp0yhxwet5v9kxy7fwvdhk6tmkxyqzq9eemymaerqvwdc25f6ctyuvzx0zt3qld3zp5hf5cmfc2qlrzdh0h075x5 .

Go there and make a list of the npubs you consider your "close friends." You can have each entry on the list considered "private" so other users won't be able to see who they are, but at least one entry will need to be "public" in order for the list to show up in Amethyst.

Once your list is saved with all the npubs you want included, pop back over to Amethyst and at the top of your home page, tap on "All Follows" and the list you created should be displayed as an option to select.

Now you have a feed with JUST those npubs' posts.