Suspicions confirmed! According to MacTracker the iMac in the ad is the oldest version that can run Ventura. Given the Kaby Lake dual core i5 processor, 8GB of memory and 266GB of storage I would anticipate the performance being somewhere between dreary and dreadful. The odds are against its being capable of this year's macOS upgrade and it may already be on Apple's antiquated list, meaning Apple only supports it on a parts available basis and it is a year or two from going on the obsolete list meaning Apple won't touch it. To paraphrase a song from my youth, ...this old mac ia s gettin' ready to meet the saints.
In my opinion, if you are willing to purchase it with the possibility that it may not tolerate the next OS upgrade or the next round of software upgrades and updates or may have to be replaced soon, it might be adequate -- just adequate -- to your needs. I have written and re-iterated the adage that if something seem too good to be true it is, this price may good, but remember you get what you pay for, headaches included.
