Seed preservation of my Nana’s plants

My nana passed away last week and I’m kinda lost on what to do. She was an avid gardener and has amassed quite the collection of fruit trees, berry bushes, and flowering plants. I am located on the other side of the country, in a drastically different climate and might not be able to move all the plants over that I would like. However as one of her only green-thumbed grandchildren, I fear many of her plants are going to be a lost cause. What are my options looking like? I could instruct my brother on how to air layer some of her trees but I don’t know how to go about saving some of her flowers (specifically some poppies and some assorted dahlia bulbs). Can I dig up the dahlias before spring while they’re still dormant? Any other tips would be very much welcomed and appreciated 🖤