I have a dedicated espresso grinder. It won't grind course enough for pour-over. If I purchase coffee ground at the store, what can I expect in terms of freshness if I keep in in one of those AirScape containers?

You might want to look at an article by Prima Coffee. They compared pre-ground coffee on an EK to fresh ground on lesser grinders.

That said, something like a 1Zpresso would win this after 1 day and isn't very expensive.

https://prima-coffee.com/learn/article/ ... resh/32594

Unfortunately you'll have distinctly less flavoursome coffee. Coffee "falls to bits" quickly once ground. Popping it in a bag once ground will not help much.

What is the make and model of the grinder you are using? That may be helpful to know.

A 1zpresso would certainly be a good option.

It'll last for 10 minutes max untill it degrades in a very rapid pace.

Buying a dedicated handgrinder for pourover is the way to go in your case. If you can buy a Commandante MK4 as they perform really well for pourover and much better then all of the standard italmill burr handgrinders.

A hand grinder for a pot of coffee is a PITA. A Baratza Encore will do yeoman service.

That prima article has me thinking some. How about grinding coffee, dosing for drip batch size, vac sealing and freezing?

Even without the freezing step, it seems like a vac sealed 50g pre ground pouch would stay good for at least a few days for travel.

For example, this past weekend, I was at my parent's house, and they have a spinning blade grinder atrocity. I'd bet that coffee ground on my grinder and vac sealed would be better.

I went to a George Howell coffee education event at his roastery several years back. One of the exercises we did was comparing the same coffee (literally the same lot from the same farm on the same year) 3 different ways - frozen, old, and stale.

The "frozen" coffee had been vacuum sealed and deep frozen as green beans, then stored this was for something like 1-2 years.
The "old" coffee was green coffee stored in a warehouse for the same period of time.
The "stale" coffee was meant to represent coffee that had sat around too long post-roast. However GH admitted that they accelerated the staling by grinding the coffee the day before the event.

We were all given each coffee and not told which was which. The frozen coffee was excellent. There were no obvious flaws. The "old" coffee was to me noticeably less "clean". It had some "earthy" character that would not be at all out of place in some coffees. It wasn't terrible, and participants were mixed in their ability to pick out this coffee.
The "stale" coffee on the other hand was gross. Simultaneously bitter and bland, oxidized, cardboardy. Nearly all participants rated it the worst of the bunch.

The point of my rambling: old preground coffee is nasty. Don't do it.

I have a Vario at home and was using a Lido 2 grinder at work for an afternoon cup of pressed coffee but decided that the convenience of grinding my 18 gram afternoon dose of coffee at home from the Lido into a tight-fitting salad dressing plastic lidded cup outweighed any loss in quality. I didn't really notice a loss in quality between grinding coffee in the morning into a sealed cup to brew in the afternoon and freshly grinding it at work with a hand grinder.

I think you'll notice a degradation in coffee buying pre-ground after the first day.

I did that for years, bought coffee at a shop and had them grind it for me. The smell in the car on the way home was intoxicating. And the coffee was wonderful on day 1. Day 2 wasn't bad either. Days 3-N were kind of the same, not bad but definitely not as good as that first day. I kept the ground coffee in a sealed container in the freezer.

More recently I ground and vacuum sealed coffee for the first week of a long backpacking trip. Opening the sealed bags released an incredible aroma. Had the coffee lost something during that week? I don't know for sure. I was happy with it.