One suggestion: A lot of folks don't go to gym, lack access to exercise equipment etc. It might be worthwhile to have a section on how to work out the specific muscles without any equipment and in minimal space using only bodyweight/calisthenics; eg. Yoga stretches, deep squats, pushups(both Normal and Hindu) etc.
On another note: technically, for forearms you'd want to have your hands facing away from you when doing a chin-up. Hands facing towards you is better for biceps.
Forearms are also one of the main muscles (groups?) targeted by rock climbing. Depending on where you live, you could likely find some boulders with very low traverses, which would require exactly no equipment (though climbing shoes would help immensely)
No you can easily do them at home by clasping your hands together and making your arms work against each other. It just isn’t as efficient as compound exercises (e.g. pull-ups that also exercise your back).
That sounds very inefficient. Here’s something that gets good results quickly. Tie a string/top to a filled 2L bottle. Attach the other end of the rope to the center of a short wooden pole. Wind up the bottle. Wind down the bottle. Repeat ad infinitum. Quick and easy.
One suggestion: A lot of folks don't go to gym, lack access to exercise equipment etc. It might be worthwhile to have a section on how to work out the specific muscles without any equipment and in minimal space using only bodyweight/calisthenics; eg. Yoga stretches, deep squats, pushups(both Normal and Hindu) etc.