To answer your original question, you should be fine for a couple weeks as long as you are able to prevent oxidation. I wouldn't push it though. If you are not ready to invest in a whole keg setup, you can always transfer the beer to another airtight container and cold crash it and keep it just above freezing to prevent autolysis (which is when there is not enough fermentable sugars for the yeast to eat so the yeast eat each other/themselves). To do this without exposing the beer to oxygen without a CO2 setup is difficult. And if you don't plan on drinking all of it pretty quickly, oxidation is really important to avoid if you want your beer to last.
However,
If you are concerned that you may want to expand, I'd definitely just bite the bullet and get a full keg setup. You don't have to spend crazy money to get a proper keg setup, but it is an investment. I find that spending a few hundred to get my keg system up and running was one of the biggest advancements I made in my brewing.
You can buy reconditioned/used kegs in packs as well to cover your bases if you think you may want to expand (link 1). I recently upgraded to using sanke kegs, and while they are a bit harder to open and close, the parts were more readily available and less expensive (I found). I worked in bars for a long time too so I'm used to working with sanke kegs.
As far as parts go, I bought my fist kegerator for around $350, and it came with everything I needed except the kegs. I found a pretty similar one on Walmart's website (link 2). A lot of those all-in-one systems (including the one linked) are for sanke kegs, but you only need to replace a couple pieces to get it to work with corny kegs or you could just go with the sankes. My homebrew shop sells a kit (link 3).
And you can always go second hand. I sold my first kegerator to a friend who was just getting into homebrewing. Check facebook marketplace and craigslist. (I do worry about buying the kegs themselves second hand, because you want to make sure they are NSF Certified and still hold pressure. If you do buy kegs second hand, take it somewhere to have it pressure tested and also replace the o-rings. When you get it, soak it in sanitizer for an hour or so and again for 5-10 minutes before you use it for the first time.)
Long story short, there is no right or wrong answer here. I personally think it is worth investing in a full keg setup. If you are thinking you may expand to more batches at a time, buy a few corny kegs. If you think you want to expand to larger batches and therefore larger kegs, go with a sanke setup so you can start with 1/6 barrel kegs (a bit bigger than a corny) and you can upgrade to a 1/4 or 1/2 barrel in the future. If you are fine with your setup now and don't want to get a bunch of extra equipment, try my suggestion earlier for cold crashing it. Or, bottle the remaining beer and share with friends or coworkers!
(1)
https://www.amazon.com/Reconditione...g=se&keywords=corny+keg&qid=1723742167&sr=8-8
(2)
https://www.walmart.com/ip/Arctic-King-Single-Tap-Kegerator-4-9-cu-ft-Black/868973640
(3)
https://annapolishomebrew.com/colle...ts/ball-lock-to-sankey-coupler-conversion-kit
