Toddler wakeup clock - better arduino choice?

Hi everyone,
I'm quite new to arduino and just playing around really.
I built a "clock" for my toddler. No display but i use a 24 pixel neopixel stitched onto a soft toy tummy.
There are buttons in each hand (on and off).

On:

  • records current time (using a arduino clock module).
    I then reduces the LED's through the night until wake up at 5:50am.
    It then has no lights and changes to orange (he can wake and stay in room )

This counts down the orange LEDS until 0 at which time (615am) he can get out of bed and the 'clock' turns green and flashes.

My issue is that I'm using a NANO in this build, attached to a USB to power it.

I was thinking of going to a different arduino, but which should i look at? (cheaper)

I'm using 4 digital and 2 analog pins.

I didnt know if i should be just sticking to this but a few friends have asked if i can make one for their kids.. so i would like to keep the USB functionality as the time forwakeup and stuff is set in the code, which means a quick plugin to the desktop to set time and then its up and running.

Any opinions /ideas for this?