Also much harder to control. Oven drying has the advantage that you can set the temperature so there's no risk of overheating anything.

I do microwave. It's pretty easy to not burn, just undershoot it - 10 seconds, see how hot it is, another 10 seconds. Once it's blazing hot shake it back and forth to get the steam off. If it's the colored kind (white when good, pink/blue when full of water) it's easy to tell when it's good. Takes about 30 seconds all together - I recharge my dessicant packs before every use. Of course, people are welcome to spend hours doing the oven method if they want. I just don't personally see an advantage, unless you have an industrial amount of packs to recharge.

FYI, but some desiccant coloring agents are cancerous

It's cobalt chloride—the same stuff that used to be used on those little weather indicators where a little man or woman would pop out to indicate whether it was going to be wet or dry. They usually had a spot of blotting paper about 2cm round soaked in it. Cobalt chloride is blue when dry and pink when damp.

All ionic cobalt salts are toxic so cobalt chloride is not used as an indicator in silica gell packaged for use with food. That said, it's an excellent indicator for telling whether your silica gell is still working or not.

Silica gel for industrial purposes sometimes is soaked in it as an indicator.

Yeah. Unless it's advertised as "food grade" and has a specific "Cobalt chloride free" I would def. not put it in food -

These fit the bill. Assuming they're not straight-up lying or anything...

https://www.amazon.com/Rechargeable-Desiccant-Dehumidifiers-...?

Unless you’re referring to strange toddlers wielding crayons, you probably mean “carcinogenic”?

is there any harm in overheating silica when drying it out?

Pure silica? It's really just SiO2. It might kind of fragment/ burst if it has a lot of water absorbed and you heat it too fast. Then everything in the vicinity would get sprinkled with fine dust which you shouldn't inhale in large quantities, as it might cause silicosis.

This is what I do to dry 3D printer filament silicagel. Handling all those small beads without spilling some is finicky, but works good enough.