Conformal coating health concerns
Lukas, congrats on being thoughtful about safety. There is a family of silicone products that are safe for human contact -- they are 'platinum cure' formulations. It's not the only source, but I like Smooth-On products because they freely provide extensive technical information.
Some of their platinum-cure silicone products are used in theatrical prosthetics and adhesives that are painted directly onto the skin, while others are specifically for encapsulating electronic devices. Your options include &quot;painting&quot; on a coating, but you could also consider making a mold and encapsulating your PCB. In any case I don't think these will harm your PCB functionality as long as you're not using RF or wireless.