You might want to get an HVAC opinion on this to get an idea how removing this heat source will affect the overall climate of the space, especially cold Edmonton winters (based on your username). In some places a fireplace like that is purely decorative. In others, however, the appliance might be functioning as an extension to your central heating system.

Looks like a very large space to heat, considering the high ceilings. Make sure whatever else is heating that space has the capacity to do so without also putting extra stress on the rest of the house. Where is the thermostat in relation to this room? If there is a thermostat in the room is it wired to the central air system? Or is it wired to the fireplace?

I don't see any electric baseboard heaters under the window. Check whether that register ("vent") under the window is supplying heat or if it's an air return. How many total windows and registers are there around the room?

If you're looking for something low profile I feel traditional drawer hardware isn't the solution.

Instead there may be rail type hardware. Try looking for a "linear rail". Similar to how pocket door hardware works, but inverse.

The forces exerted on a hanging load like this pose an incredible challenge on both the hardware as well as the fasteners.

Speaking from experience, I once built something similar using two heavy-duty full extension drawer slides mounted to the underside of a desk. As long the load was simply suspended it was relatively solid, but after only a few months of regular use the ball bearings started to fail.

The challenge is the force of gravity acting on the slides which are designed to be used in a vertical orientation. Those forces are compounded when the hardware is open and rotational forces also apply.

Is this going into a cabinet, have you considered using traditional hardware but mounted against the top of the carcass, with your "drawer" hanging from it? (Similar in concept to the pantry slides someone recommended)