Which island? Skye, for example has a thriving local food industry. Lewis maybe more difficult, but like where I am there are a few people determined to change things.
DO acquaint yourself with the CAAGS grants system. You get 50% for alot, but you need to plan in advance & be really organised. You also need to be able to pay out 100% of the costs & once the work is completed you get your 50% back, but it takes time. For some things I have found it easier to do it off my own back.
I agree with most that has been said. Try to aim for the local market & mail order ( It is much cheaper to send things
from the Highlands & Islands). Think outside the box, using one of the buildings as a bothy is a good idea.
I got my croft nearly 3 years ago, not as big as yours, but some of it was very wet, so I focused on draining this area & established a pond in the wettest bit. A heron uses it & this year the wild ducks came in. Yesterday I was able to start ploughing

.
My first income was from pigs, who turned & manured the land & hens ( eggs), who also turn over alot of ground & eat bugs. The croft currently feeds us & we probably break even at the moment if you don't include costs of machinery, pig arcs & the other larger fixture & fittings & major works. There are still longer term projects that I hope will bring in an income, my husband still works.
So I would look at short, medium & long term, so that you get some return early on, while working towards something a little different that may need time & experience to establish.
Good Luck, whatever you decide, you should love it