1xxx, 3xxx, 5xxx, and 6xxx aluminum alloys are widely used in food processing equipment - those alloys are considered to be safe for food contact by the National Sanitation Foundation (NSF - not the National Science Foundation) and other regulatory agencies, and is explicitly approved under NSF/ANSI standard #51 for food contact in all circumstances. Also everyone wraps their food in aluminum foil without issue, and uncoated aluminum is frequently used for peel-off lids, disposable trays and pans, and food utensils.
You should be more concerned with lead solder, which is widely used to solder together keyboards. According to the CDC. “Washing skin with standard soap and water is not enough to remove lead residues.”, and you should be using special lead-removal wipes such as D-lead after soldering. Or use gloves, or switch to lead-free.
Leaded brass alloys such as brass C360 is also frequently used to make items such as weights and badges (lead-free brass tends to machine poorly), though those surfaces are touched much less often than keycaps. Brass C360 contains around 2% lead, but much more is present on the surface as the machining cutters smear the lead on the surface.