"Whatever you do, please don’t buy a VacuVin or anything resembling such a device that allows you to “pump out the air from the bottle.” These devices just don’t work as advertised. Sure, they remove some air, but not enough to truly protect the wine."
So I guess we'll just finish the bottle!
For a $12 thing, it's not a huge investment to get one and see for yourself whether it works or not.
That may be the case, but I can assure you that a very inexpensive "brake bleed kit" with a vacuum gauge attached will, indeed, vacuum the headspace and maintain that vacuum.
Again, you have a gauge with mmHG or whatever and you can verify that the vacuum is unchanged.
I speak elsewhere in this HN thread about displacing air in primary fermenters with CO2 but I have also removed air with a hand vacuum (brake bleed kit).
That said, reading about the eto has sent me down a rabbit hole on Amazon. I’m seriously considering ordering a wine squirrel now!
What I have noticed is that some bottle necks are slightly too large or of a weird form for the corks, letting the vacuum escape. When everything is OK the cork makes a pleasantly sharp "ssssshhhhup" sound when releasing the vacuum. For some bottles there's just a faint sloppy "shh" or perhaps even nothing, and for sure the taste isn't optimal then.
After pumping I always put the bottle to the fridge. If storing a pumped wine at room temperature I suppose the wine would quickly end up tasting like donkey.
Then later, when it's time, I open the cork and let the wine warm up (!) to the required temperature.
A pumped wine won't hold for months of course, but I've kept more robust red wines up to a few weeks max, and they are OK for my tastebuds.
So, after any decanting and airing I usually test the bottle with the pump + cork, to see that it gets sealed properly, if I plan to pump it.
Probably all Frenchmen and Italians are rolling their eyes and writhing in agony now but hey, it works for me...