If you're trying to produce a piece of T&M equipment, I'd argue that for the reasons you've highlighted, running Android on it could be a huge mistake.
A piece of T&M kit is not a mobile phone. It's not a device which is sold on how nice it looks, and on how many completely different uses it can be put to. It's not a fashion accessory, nobody will be playing games on it, and more than likely, no third parties will ever write software for it.
The product needs to do one thing, and to do that one thing exceptionally well to the exclusion of all else. Its UI needs to be effortlessly responsive, and anything which gets in the way of its one and only software application accessing the UI controls and underlying hardware can only be a hindrance.
As you've probably gathered, I'm very much opposed to the use of PCs and phones as T&M devices. A PC is a useful logging and post-processing tool, of course, but as a way to operate a measurement device directly, clicking on things with a mouse (or, worse still, poking at pictures on a screen with a fat, greasy finger) sucks compared to real knobs and buttons.
You refer to a GUI not involving knobs or buttons as "modern", but I'm afraid I disagree. Such a GUI has its place on a phone, for entirely practical reasons, but not on a piece of T&M gear. Choose a UI that really works well, not just one that's fashionable this week.