IKEA just released a pleasantly priced bluetooth speaker KALLUP.
It is not hard to get it converted into a homeassistant player 
Based on the info from this forum thread about retrofitting the IKEA VAPPEBY speaker by @formatBCE it was rather easy to get the new speaker integrated in HA / musicassistant.
KALLSUP speaker with original bluetoooth board and battery.
Replacement board, consisting of a XIAO ESP32-S3 and a MAX98357A DAC.
Two buttons soldered on the back of the board, fitting to the buttons at the top of the speaker case.
All is fitting quite easily. The battery is not used.
Closeup of the buttons.
The 3W speaker is sounding fine for the money paid.
Integration in musicassistant was easy, with the new (still experimental) sendspin streaming protocol also good for synced multiroom sound.
The connections for the XIAO ESP32-S3 and a MAX98357A DAC were:
I2S LRC → GPIO07
I2S BCLK → GPIO09
I2S DIN → GPIO08
GND → GND
VIN → 5V
The buttons are connected to
Button 1 → GPIO04
Button 2 → GPIO43
both → 3,3 V
The setup is also working with the new ESP32-C5, with the possible benefit of 5MHz Wifi.
First test with the C5.