Hi Op, and yes. The way i had to tackle my parent situation was to work close to their preferences . I realized what worked for me may not fit your dad's preferences but you can look up substitutes.
In my case it was encouraging more of what they ate occasionally. Eating more bone broth and tripe (collagen/gelatin/Glycine), there's always stock in the freezer now. Tripe, spleen, liver for minerals and enzymes. Jello.
Swapping over to Quali-C for Vit-C, it works with Glycine. Cherries, including juice and especially tart varieties, have a good nutrition profile and help with inflammation after exercise, along with sugar borates which can help with certain bone and joint issues in low dose. Calcium fructoborate pills are sold but don't neglect whole foods and mind the overall Boron intake if combining pils with foods.
Aspirin has a role with inflammation especially in the long term and many other supporting roles of course.
Vitamin D/sunlight, Magnesium ideas seem sound. And remember that Vit-K2 has many forms but the MK4 and MK7 seem the nost useful. Some folks go fairly high dose on the MK4. This form is worth the extra research imo as i recall it having a direct role especially in higher dose.