Since it's not listed in the known brands, your only choice is to chose other manufacturers and hope you find a code that is compatible. After a little bit of googling I found this question on Amazon that was answered by the manufacturer, so it might be a good place to start.
"Q: What brand do you pick to program this with the fire stick remote? Phaeoo isn't listed.
A: Dear Valued Customer,
You can use the ABox soundbar brand for Pheanoo D5/D6 and use the Boat soundbar brand for Pheanoo P27/P28/D2 in the soundbar selection of the FireTV stick equipment setup.
Thank you"
Alternatively, you can try to learn the remote commands from your original remote, you should see that option in the remote menu before you chose the pairing wizard. A little more involved, but it should work if the original remote emits IR like most other remotes.