You have to use the "nevent" tag for the embed to show in noStrudel and other apps. Unfortunately nostr:npub1stemstrls4f5plqeqkeq43gtjhtycuqd9w25v5r5z5ygaq2n2sjsd6mul5 doesn't have a good way of copying the "nevent" for the track. so you have to create it manually

Steps manually get the "nevent" of a Stemstr track:

1. Copy the track id, its the part in the URL after the "/thread/". it should be a bunch of letters and numbers

2. open https://nak.nostr.com/ and paste it in

3. There should be something that says "nevent". Click the little pencil icon right next to it

4. Click "Add relay hint" button and enter "wss://relay.stemstr.app" into the field and press "Enter"

5. Copy the "nevent" string in the input and paste it into any nostr app with a "nostr:" prefix

example:

nostr:nevent1qqsdmdq5g45jarht8fq3k9p2lwdyaau6arv620eryf9vzfyy5tcxp8qpzamhxue69uhhyetvv9ujuum5v4khxarj9eshquq3r2eth

I wish this wasn't such a manual process right now but hopefully Stemstr can add an easy "Copy nostr share" button or something.