Thanks for your investigation.
My device is a Samsung Galaxy Tab S2, codename SM-T810.
And, for what it's worth. the useragent string is.
Mozilla/5.0 (Linux; Android 7.0; SM-T810 Build/NRD90M) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/66.0.3359.158 Safari/537.36 OPR/47.3.2249.130976
Based on your investigation it seems that Edge updates the search site to Bing, but this can be changed in the Edge settings. But worse is that it also hijacks the browser. Bad.
Please keep me informed about your conclusions.