If you're going to be pedantic, electric charge (if any) will reside on the outside of an "anti-static" bag, not the inside. Resting a board on the outside of a bag is not safe in all circumstances.
I've worked for large companies where they've spent millions of dollars equipping labs and production facilities with ESD protection. When you're flying at 33,000ft/10,000m, you don't want the electronic avionics suite to lock up, because someone ignored ESD handling precautions in the factory. (Yes I know they have backup systems in planes).
https://resources.system-analysis.c...handling-procedures-for-sensitive-electronics
In the home, it's normally sufficient to touch the metal computer case if it's earthed, before pulling the motherboard or GPU out of its ESD bag. You're trying to minimize the potential difference between the two parts you're assembling.
The crucial thing is NOT to walk about on a carpet before touching any static sensitive components, especially CPUs and RAM. Two or three steps across a dry carpet can be enough to charge your skin up to several thousand volts. You pick up the component and Zap!
I use a large ESD rubber mat spread out on a work surface and an anti static wrist strap with coiled lead when working on PCs. The anti static mat is connected to mains earth through a special lead with a 1MegOhm resistor. I place everything on the mat before assembly and keep the wrist strap on at all times.
Most people get away with zero anti static protection at home and never have a problem. The trouble is, if you don't observe ESD precautions and a component eventually dies, you'll never know if you zapped it with static. See electron microscope picture of static damage (right hand image).
https://emfsurvey.com/esd-electrostatic-discharge-testing-sensitive-equipment-electronics/
Good luck. It may never happen to you.