I skipped Bluetooth and went straight to Wi-Fi speakers. You can get a Google mini on sale for like $30. JBL used to make a really nice Link Portable that you can sometimes find on Ebay that came with a charging base you could just leave it on. I have one of those in my attached garage. Altec Lansing used to make the Live2Go series, which are also on Ebay. They had both a battery and wall powered unit, with the battery unit being IP67 waterproof. I have one of those out by my pool. Get a Spotify account. Make sure you cast my friends band, "Frank Muffin"
JBL is still making Wi-Fi speakers, but they are pricey. Altec Lansing only makes Bluetooth stuff now.
I may switch everything to Sonos if I ever find a good deal. They are the best Wi-Fi speakers.