A low-risk way to dip your toes in is to email a blogger to say that you enjoyed their post or that you found it helpful. The message doesn’t have to have useful information in it, just be sincere. Per OP, often there won’t be a reply but also often it’s much appreciated - particularly by non-mainstream writers.
So every now and then, I spread some joy by sending an email to a complete stranger.
And I always add that I don’t expect a reply, so they don’t feel obligated to respond.