Small Dily3217 Arduino compatible ATtiny3217 breakout development board in a DIL24 package
See the article here: https://www.avdweb.nl/arduino/dily3217
The ATtiny3217 is more powerful then the old ATmega328P.
The Dily3217 works the same as an Arduino Uno or Nano, you can simply upload sketches via the serial port because it has a bootlader.
The difference with the Arduino Uno is:
The supply voltage is 5V, there is no voltage regulator on board.
An external FTDI board is required for programming via USB