Any guitar effects unit with a headphone jack can drive speakers loud enough to be used as a practice amp. Headphone circuits are generally 1/3-1/2W, which is plenty loud enough for playing alone in a room thru a small speaker.
In my video, I connect the headphone jack of my old Digitech RP7 into a 12" speaker cabinet. Works great!
PS: be sure to use a STEREO cable, NOT a regular guitar cable. Using a regular (mono) guitar cable can short out one side of the headphone jack.
Your mileage may vary