100% Danish here. Grandma made rye bread all the time and I’d love to have her recipe but likely it was never written down. I’ve used Sturdiwheat brand rye bread mix and it’s good but not as dense as I remember. A box of 4 mixes is available online. Pinterest sells a Swedish rye bread recipe that looks good but I’ve not tried it. I use about equal rye and white flour if I make it from scratch. I know it should contain a little molasses, cocoa powder or even kitchen bouquet.