There is different hardware on the market available to convert a passive speaker to an active one. Here I present a variable solution with Bluetooth and the possibility to control it with an MCU.

• passive speaker
• amplifier (here: TPA3118)
• power supply unit
• DC-DC decoupler / filter (to eliminate noise of PSU)
• receiver/player (here: BT201 KT1025A)
• MCU (optional)

TPA3118 class D mono amp
BT201 module with KT1025A
MeanWell SMU01L-05 DC/DC Wandler, 5V zu 5V, 200mA, 1W

What is different with this module from other common ones: It has RX/TX lines for AT-commands, so it's easy to use an MCU for setup and controls.
It also has iR for a remote control. It can play audio files from Bluetooth, USB, SD-Card, AUX.

https://web.archive.org/web/20240615231859/https://nettips.ru/book/BT201%20Module%20_KT1025A_B_User%20Manual%20_V2.3.pdf
https://elektrotanya.com/kt1025b_bt201_bluetooth_audio_chip_user_manual_v2.4.pdf/download.html
https://www.electronics123.net/amazon/datasheet/FN-BT91%20(BT201)%20Bluetooth%20Audio%20Player%20Module.pdf
https://www.scribd.com/document/857956764/BT201-Module-KT1025A-B-User-Manual-V2-4

example code links:

https://github.com/MooreSound/code
https://github.com/mehdi-adham/BT201
https://github.com/christian-kramer/JieLi-AC690X-Familiarization/issues/4

The amp needs >=12V, the player 5V. There are different choices as PSU:

For >=12V:

• Use a random AC-DC power supply unit
• Use USB-C PD trigger (module): see USB-C-ify everything

To get 5V:

• 5V module (either switching regulator or LDO): switching introduces noise, an LDO heat an inefficiency
  • use a 12V car cigarette 5V USB adapter
    

instead of 5V DC DC decoupling module, try if an LC filter is sufficient:
#TODO: add schematics

If voltage of your PSU is suitable, use an LDO to smoothen power input for receiver/player module