I detest silica gel bags.
- It’s a bag. You have no idea what’s actually in there.
- You have no idea how old it is. It may already have absorbed as much moisture as it can.
Better to buy some loose gel (always the colour change variety) and put it in a container you can see into. Hell, even a very fine cloth/gauze bag would do.
Then there’s the issue that it’s just lying there on the bottom…inefficient without a fan to pull the air through.
That’s why I looked at the Arduino driven idea.
it’s all 5v, so in theory you could run it off a mobile phone recharger, or even a plugin USB cable. You could design it to all fit in one plastic enclosure (I’m not familiar with the Sunlu driers design, but there must be space to tuck SOMEthing in there).