The alternative is to use multiple Echo devices. For the best sound, you can get the Echo Studio, which according to Amazon is their "best-sounding smart speaker ever - With Dolby Atmos and Alexa." It's around $200.
Amazon Echo devices use WiFi to communicate between devices. They have more control over latency as well as a small buffer that can pick up the slack in case of poor signal. Bluetooth has no buffer; It just plays what you send it, and if it doesn't go through, too bad.
If you want to go a cheaper route, you can get Echo Dots and place them all around the house. Echo Dots can be had for around $30 or less when they have a sale (Black Friday, Prime Day, etc.) Of all the different Echo Dots, I think the Echo Dot v3 & v4 sound the best, but v4 costs more. Dot v1 & v2 sound pretty terrible, like a tin can.
If the reason why you want to use Bluetooth is because you want fully wireless with battery, there are some 3rd party manufacturers that make a battery base for the Echo Dot. They have battery bases for all versions of Echo Dots from various manufacturers and sellers. I got one last week from a local auction for $2. But Amazon sells them for around $30 or so. Attached is a photo of it.