why not rent the land to a farmer for a bit?
you cant keep a cow on her own, it wouldnt be fair and they are more than capable of jumping out and finding the nearest herd (speaking from experience

). a cow per acre is the bare minimum and i guess this equation is based on summer grazing which is excellent grass and rotated each year, i dont think it means a one acre field is suitable for a cow on her tod. cows eat alot and also poop alot which reduces clean grazing. keeping one cow per single acre year in year out would require a degree of land maintenance, and would require bring the cow inside for the winter to rest the field. all cows kick so be prepared for that.
i dont think cows or sheep are low maintenance as they require some commitment in terms of educating yourself about them. we have kept cattle for 3 yrs or so and still feel like a novice. i do prefer cattle to sheep though as they are so calming. but they do require more ability in handling. plus they require tb testing etc at only a few days notice.
sheep are maybe easier if you are prepared to bucket train them check them regularly for flystrike etc in the summer. they wont make so much mess with poop but can be infuriating if you cant catch them without a dog

they do sometimes do bad things like jump on your head if penned up

sheep are much easier to finish and send away, whereas cattle take almost 3 yrs. sheep are easy to sell even if they are poor pedigree as there are many pet homes around, whereas this might not the the same for cattle.
the initial investment is less for sheep.
having the house cow sounds lovely but you do need to get her pregnant, by AI or transporting her somewhere (need trailer and 4x4 - so gets expensive, plus movement docs) , she may need scanning so you might need to invest in a crush etc and then you need to sell the offspring etc or you'l be over-run with cattle.
we kept 5 native sheep on an acre all year round with only a small amount of haylage and hard feed in the winter.
you have to decide if you want neutered pet sheep or young ones for meat. native breeds are much more suitable for novices than the hybrid mules.
its alot easier and cheaper to rent the paddock out.