Just to offer something at a different price point, I've had
these Pyle Audio outdoor BT speakers from Amazon for about 3 years now and I've been perfectly happy. I just wanted something hard-wired that would always be there, so I didn't have to haul or charge a portable solution, and I didn't want to have to cut into the soffit or run a bunch of wires yet. These just have a power cord and a speaker wire to the slave speaker and a couple screws in each mount. About 15 minutes to install.
For around $100, I thought they'd be temporary while I looked into other solutions (perhaps something whole-home like Sonos) but I really like them. Plenty loud, decent sound, and I think I prefer the bluetooth for its versatility, as opposed to having to run everything through the Sonos app.
I keep an old echo dot out there, so I can control hands-free while in the pool, but I can easily tell it to disconnect and connect a phone or tablet to play audio from anything (YouTube probably being the most notable one that I use pretty frequently and you can't play through Sonos without a paid subscription).