Just a couple things to point out…
Is this the very same NUC you posted about a couple times in 2020? You sure that thing is ok? It seems like you had a multitude of problems with it.
Even if you get NC set up, or even if you pay someone to do it, you will have to maintain it yourself. That means regular system updates and maintenance, and done correctly. While I or many others could easily do the setup, I personally would not be willing to take on the risk that you have some problem (hardware problem, update problem, totally unrelated network problem, etc.) and then have you wanting a refund in a few months.
Now, that being said, since that time, we’ve had Nextcloud AIO come out which is super easy, and I also wrote a guide for setup with Docker. There are several fairly easy options available now, and people willing to give advice and troubleshooting.
But I think asking for a guarantee of reliable availability is going to be a stretch, due to factors beyond our control, and also that we seem to be potentially talking about a setup without port forwarding.