I built a silent (except for a barely audible CPU cooler that barely runs) using an AMD M1 CPU a while back. It's in a nice little mini-ITX case and runs Win10 very well. It was quite inexpensive as well (much cheaper than an Intel NUC at about $200 + third party CPU cooler + RAM.) Unfortunately, AMD discontinued that line of CPU. Tried an Intel NUC with a mobile CPU but it was an absolute disaster in performance and it was overpriced.
Adobe Flash is an issue and it's going away soon. In a year or two all browser support and vendor support will be gone. Then it will be an even worse security issue.