Wait a second. Firmware for Pebble is one thing, Beta versions are for Android phone. You can sideload whatever version you want, taking into consideration that 2.x firmware should go with 2.x Android phone App. You can even use PebbleBits.com to upload an extended version of the firmwares...
[ACTUAL SET] LG NEXUS 5, KITKAT 4.4.4 STOCK + GRAVITYBOX
[HISTORY] PALM OS:M500/M515/T3/TX/TREO680// SYMBIAN:N95/N97(NOKIA)
ANDROID:MILESTONE(MOTO), NEXUS ONE(HTC), ATRIX (MOTO), SGS2, GALAXY NOTE, SGS3 (SAMSUNG), ONE X (HTC), NEXUS 4 (LG), XPERIA ZL (SONY)