Adafruit did a board Adafruit I2S Stereo Decoder - UDA1334A Breakout : ID 3678 : $6.95 : Adafruit Industries, Unique & fun DIY electronics and kits that is discontinued as they now do it as a hat for US$9.95 but the modules are still on aliexpress for $2.50 if technical means you can solder a few header pins then x3 dupoint jumpers on the pi & x2 power as actually I prefer then than a hat that obscures the Pi heatsink.
Either Hat or module think they are the cheapest you can get and sound pretty great as I have 1x bluetooth with 2 speakers synced with snapcast but pointless with anything better as the bluetooth codec sets max quality.
For Raspberry pi HIFI PIFI Sound Card I2S SPDIF Optical Fiber Module WM8804G | eBay
I use one of these with a 3B+, sounds great!