Ensuring proper moisture content in long-term food storage

New to long-term food preservation. As I understand:
1: Only certain foods can be stored using oxygen absorbers, generally, powdery foods are out, and "moist" and "oily" foods are out.
2: Moisture content of the food must be at/below 10% (higher and bochulism is an issue, too low and the oxygen absorbers can't work since they operate via iron/rust reaction which needs H20)
3: Silica packets do dehydrate food, but uncontrollably. Therefore, they cannot be used in combination with oxygen absorbers.

My question is: How do I safely create a consistent moisture content in the foods stored, so that I can have assurance that they are within the acceptable range for oxygen absorbers?
Bonus question: How do I inspect food stuffs before consumption to ensure they are safe to eat? (aside from the obvious broken seals) For example, smells to check for, or purchasing more "pink dot" stickers that come with absorbers so that one can be added to each container...?
Money question: Does anyone have a cheat sheet of foods and storage methods/amounts including oxygen absorbers, silica gel packs, diatomaceous earth, etc?

Best information sources I've found so far:

https://www.thesurvivalistblog.net/oxygen-absorbers/#How_Are_Oxygen_Absorbers_and_Silica_Gel_Different

https://www.churchofjesuschrist.org/topics/food-storage/longer-term-food-supply?lang=eng#1

https://www.youtube.com/watch?v=P5nkbB_UsP0

https://www.youtube.com/watch?v=dn0uESzlOvo

Based on this paper there is no good way for developing countries to accurately measure/control moisture content. https://www.sciencedirect.com/science/article/pii/S0924224418304898

I have been doing food storage for a long, long time.  Remember Y2K? I was doing food storage before that event.

I refuse to pay money for the "oxygen absorbers, silica gel packs, diatomaceous earth, etc".

White flour, white rice, cornmeal have all worked fine for me without buying those items.

All sugars have worked for me without those items.

Salt has worked for me without those.

Foods that have a short storage life, like brown rice, dry beans are best rotated to get them used up.

A good question is how many months advantage do the "oxygen absorbers, silica gel packs, diatomaceous earth, etc" give over not using them?