P E R M A C U L T U R E !
Ok, but seriously, look into making plantings that are perennials not annuals. So that means you could plant a hedgerow of berry canes or bushes and only have to mess with them about 8 days a year. That way the maintenance is low for aging parents, but the return is high with baskets of fruits. Nut and fruit trees are good options too. The more you plant plants that grow back after being cut, the less work you have to do each year. Maintaining perennials is much easier than annuals. No seed starting or replanting each yer. They just grow, then harvest, then you cut them back, then they grow again. Plus that might be good for your father who seems very project-driven, wanting to dive right in. A small annual vegetable garden with the rest being perennials will make life easier.
Also, try to plant open-pollinated or heirloom varieties of plants, not hybrid or GMOs. OP/Heirloom plants reproduce on their own naturally and you can save seeds from them each year to plant the next and they breed true. Meaning that they just keep on giving. One packet of bean seeds and you have a lifetime supply of bean seeds. Hybrids/gmos will often not breed true and some GMOs are patented and require contracts to grow. I suggest seeking out smaller seed companies not associated with large agriculture operations and rolling with them. I buy from High Mowing Seeds in Vermont.
Livestock wise, rabbits are low maintenance, giving furs and meat and potentially sales for pets, show or to other homesteaders. They're fairly efficient and take up very little space. With a gravity feeder and extra water bottles (or a tank system) they can be left alone for days without incident much like a cat.
Learning to hunt and fish is a good choice. Many wild animal populations, such as deer in urban areas, wild boar in rural areas, or invasive carp in lakes, need controlling and without hunters/fishers could get out of control and require government intervention. Just make sure you eat whatever you bag and don't go for exotic animals or animals whose numbers are threatened.
Don't discount the idea of becoming more self-sufficient in the home. Sure you can chop wood for your fire and dig in the mud for potatoes all you want but there's tons of in-home things that get overlooked because they're not as rough and tumble. But they're important. Learning how to make your own clothing, can your own food, cook, make your own broth, use feathers in crafts, make your own housewares, bake your own bread, knit, crochet, paint, make furniture, upcycle, soap making, essential oil collection, brewing, etc. This things are useful, fun, and keep your mind sharp even on days when you're sick or it's winter. I know lots of men taking up these things as hobbies because they're just great things to do with your life... As well as shifting attitudes towards "can you imagine being a grown man and not knowing how to cook, bake and clean? What are you, a toddler?" type of thing because they ARE good to know, they serve purposes, and they are equally (if not more) essential life skills compared to gardening or raising chickens. Not to mention they're challenging and fun. I know many a carpenter/handyman who can't sew a button back on to save their lives, even though that could save them buying an entirely new pair of pants.
Try to reduce your waste by swapping plastics for glass. We use glass all over our house now. This is especially nice because we're all adults so it's not like some kid is gonna break em. Pay attention to packaging when you buy something and try to reduce, then reuse, then recycle.
Or how about learning to repair minor problems with electronics, appliances, vehicles, etc? Maybe learn enough to wire your own solar panels? To debug your own computer? To fix your own plumbing? These are "modern" problems, so they're not popular to fix yourself, but they're still things you go outside your home for that you could learn yourself. Self-sufficient doesn't just mean raising your own food, it means not having to go to other people for goods and services.
In that same vein, and in the vein of livestock keeping, make a study of first aid and herbal remedies, what works and which are nonsense. (EX, crystal therapy is a placebo at best, whereas plantain(plantgo) leaves are a genuine antiseptic.)
Get into composting. Compost everything. Animal bedding, kitchen scraps, cardboard boxes from shipped goods...
Pop onto Craigslist and look for free firewood. Build yourself a wood oven outside, chop wood to heat your home in a fireplace, etc. Participate in earth day and plant a few trees each year to help replace what you're burning.
Lots of ways to become more self-sufficient that doesn't involve dairy animals. Just gotta recognize the needs or your family and environment and dig deep.
