Golden retriever grooming problems

My golden is about to be 12, and I’ll admit he’s always been absolutely horrible to groom. He was a rescue from a puppy mill so he’s always been terrified of everything; vacuum, blow dryer, baths and showers... One thing he doesn’t mind is getting brushed though. I’ve noticed the last few weeks he’s shedding much more than usual and started getting some dandruff, which is no surprise since he doesn’t get bathed regularly in the winter due to his anxiety. I’ve never medicated him and would hope to avoid this but he can’t go to the groomers anymore - he is the sweetest dog in the world but knocked the groomer to his knees (he’s not a small guy!) when he tried blow drying him and now he won’t even go near the place; our groomer has to come out to our truck to clip his nails now 🤦🏻‍♀️

As my boy is getting old, realistically we don’t have as much time with him as we’d like, so I just want to make him comfortable while still taking care of him. What can I do besides giving him meds to help calm him or what are some good foods/tools that can help with the excessive shedding?

I’m not looking for judgment here - I’m well aware goldens are a high-maintenance breed and we’ve done our best to care for him in his almost 12 years and intend to do so for the remainder of his life. Just need some advice from others who have dogs suffering from anxiety and grooming problems. Thank you!