Elevation too high for food forest?

So apparently I'm in the mountains here in TN. I always forget because when driving there, it's not steep enough to notice. My altitude is 1880 ft above sea level. I'm wondering if fruits can still grow quick enough here? Would anyone know the rate it grows compared to lower land? 50% slower? Not enough yields? How about herbs and veggies and other foods?

There are many human settlements much higher than this. They grow food. You might concentrate on varieties that are from further north, than your neighbors on lower ground.

There are varieties of fruit grown on the Canadian prairies. There are pawpaws growing in New York and Southern Ontario, Canada. Some work has been done in trying to make these grow further north. Some of these improvements, should translate to growing on mountains further south. There are also fruits and vegetables grown at high elevation in China, South America and other parts of the world.

2,000' isn't that high, especially considering how far south you are. For reference, here in California — a bit further North — the ideal elevation for growing apples and cherries is around 3,000-4,000ft. However there are plenty of apple trees here around where I live at 6,400ft. Palisade, CO is famous for it's peaches — and they're at almost 5,000ft and much further north than you are.

Elevation itself isn't a good indicator of whether something will or will not grow, a better measurement is Growing Degree Days (GDD) which tend to vary from plant to plant (using a different base temperature). You might compare your GDD to ones further down the hill to see what kind of difference there is. But every plant responds differently — some produce lower yields (shying away from flowering when it's too cold), some take a few more days to maturity, some end up sweeter, some don't care at all. the biggest challenge I've found growing at high elevation is the weather volatility — specifically early/late frosts. The higher in elevation, the easier it is for the temperature to drop at night and trigger a frost a month or two earlier than anticipated.

In any case, I don't see 2,000' TN being a significant challenge other than perhaps needing to select slightly different varieties than your neighbors down the hill.

Here in the Rocky mountains, my experience is that a change in elevation of 300 feet is approximately equal to one climate zone, and two weeks difference in first/last frost dates. For example, my last spring frost in a mid-elevation field is on about May 23rd, but the average last spring frost in my field that is 300 feet lower in elevation is about May 9th. And I don't plant frost sensitive things in my highest elevation field till after June 5th.

Some plants do better in the warmer temperatures of the lower elevations, some plants grow better in the cooler temperatures of the highlands. One way to figure it out is to just plant a bunch of stuff, and see what thrives. And pay attention to what the neighbors are growing. They aren't all knowing, and have been highly influenced by culture, but nevertheless they have accumulated hundreds of thousands of years of growing experience in conditions that are very similar to your place. As examples, the neighbors near my lowest elevation field grow huge acreages of peaches. 600 feet higher in elevation, I see an occasional sickly peach tree around, but they don't really thrive. However, the neighbors near my highest elevation fields grow lots of apples, and they thrive there. Grapes thrive in the area near my mid elevation field, but are not as productive near the higher and lower elevation fields. The lower elevation field gets more disease and insect pests, the higher elevation gets more winter damage.

I am seeing climate warming in my area, and genetics are getting more cold hardy, so I'm continuing to plant peaches, even if the trees have been unreliable and prone to failure in the past, I'm harvesting delightful peaches some years. Which was unheard of when I was a kid.