My company has 6 engineers and 2 non-engineers. Our next hire would be another engineer. This is because we make stuff. The stuff is very important. We want the stuff to be better than stuff from other companies. The way we make money is that people buy our stuff, and they buy it because it's better.
The CEO (and the unnecessary COO) don't have to understand the tech challenges, but if they don't respect them, you guys are in for a rough ride and a lot of finger pointing at the end.
It sounds like you have limited experience managing expectations in a work environment. This is very important skill, I'm sure you can learn it. The basic approach goes like this:
Everything you are responsible for delivering should be approached as a form of negotiation in which your goal is to lower the expectation to the minimum possible target, and also a target you are supremely confident of hitting (with lots of buffer). If you can over-deliver great.
No-one else can tell you what is possible for you to do or make you agree to a target (but they will try). Just say no. I understand this is tricky when you are not experienced, but it is a magical experience to watch a seasoned developer handle a situation where they are being pressured to agree to unreasonable deliverables and they gently use their confidence, experience, and scheduling/estimating aikido to avoid committing to anything they are not 100% confident about.
Once you do agree to deliver, you are completely on the line, even if you were badgered, bullied, and pressured into it. So just say NO. Not saying no, will later be treated as if you said yes. If someone else sets the target and you disagree, write it down, email it, make it known loudly that you "DO NOT BELIEVE THE TARGET IS POSSIBLE" and what resources you do believe would be required.
It's seductively easy to let yourself just go along with the consensus and feel like you expressed some doubts and then later have everyone turn around and hold you responsible. With experience, you become very alert to the red flags that this kind of situation is about to develop and you learn to ramp up your emergency prevention measures immediately. If you work with high-quality people, they will also eventually learn that they should trust and respect your estimates even if they really really really wish everything could just be done faster with fewer resources.
Good luck.