Dimming pocket outlet that remembers last set level?

You could fix this with a custom DTH. I wrote this to simulate on/off fade dimming for GE ZigBee switches. I would guess this should work for you. Available from my jhamstead/jhamstead GitHub as well (updated there).

GitHub:
https://raw.githubusercontent.com/jhamstead/jhamstead/master/devicetypes/smartthings/enhanced-ge-zigbee-dimmer-power.src/enhanced-ge-zigbee-dimmer-power.groovy

As a note, when using the ZigBee attribute to turn on at a specific level, this changes the off behavior. When turning a switch off it will report the dimmer level as 0% but will turn on to the last level.

Also you may need to add this fingerprint:

fingerprint profileId: "0104", inClusters: "0000,0003,0004,0005,0006,0008,0B04,0B05", outClusters: "0019", manufacturer: "CentraLite", model: "4257050-ZHAC"