The Peggy 2 (or 2LE) can do it, but it is indeed overkill. Probably the most straightforward way to use it would be to wire up 6 rows rows of 10 LEDs each, meaning that you’d need to run a total of 16 wires to the Peggy.
I’d estimate battery lifetime under this set of circumstances as about 150-250 hours if the LEDs are on all of the time, and 2-5 times that if the LEDs are flashing intermittently. I’d certainly recommend turning it off when not needed or (much better) using a plug-in power supply.
Since you don’t need all that many LEDs, and they don’t need to be on all the time, you might consider using Charlieplexing, directly from a microcontroller, to drive the LEDs instead. For 60 LEDs, you could do this with a microcontroller board like our Diavolino, using 9 digital output lines to drive a hand-wired matrix. For a bit more about Charlieplexing, see our article about how the Bulbdial Clock works: