If you are willing to invest an “above-minimal” amount of your own time, why not build your own “One ETF”?
If instead you want to invest minimal time only, why pay someone a crazy TER to build a “One ETF” for you instead of building yourself (again, with minimal time) a very small portfolio consisting of a few well established low cost ETFs that satisfy your needs (e.g. the ones already suggested by @xmj, as well as others, offered by Vanguard and others).
Regarding your ETF suggestion: I happen to work at a small asset management company that produces multifactor funds in multiple flavors (geolocations, risk profiles, etc). My candid description of these products: the “multifactor” argument is used to justify TER; it does not provide alpha (performance above the benchmark index) in any statistical sense.
If somehow you are interested in building your own “One ETF”, see this blog post by @DividendGrowth for why this might make sense. While it’s written from a dividend (growth) perspective, you can cross out the word “dividend” in the blog post and you get the same arguments for building your own ETF versus buying one.
If you’re indeed interested in building your own ETF, feel free to also check out my post about it* or check out my personal “One ETF”.
It’s certainly not for everyone, but if you are interested and are willing to invest time, it can be satisfying.
I personally love it!
If this was not at all the answer you were looking for, I’ll happily show myself out (of this thread). 
Oh, and welcome to posting to the forum!
* Ok, ok, the post is about picking stocks … but pick enough stocks and you have the equivalent of custom “One ETF” tailored to what you’re trying to get out of the “One ETF”.