Chrome OS has first class support for Android apps nowadays. You can use a keyboard and mouse through USB OTG or Bluetooth on an Android as well.

Something that has been with Android since 3.0.

Really wish i could find an android tablet with a full size A port these days that didn't run a ancient version...

Android has long has deep support for keyboard and mouse navigation where this could be more useful.

Indeed. It is one of those things that seems to go unspoken of, because even Google don't want to acknowledge that they once tried to pitch Android as more than a media consumption platform (Android 3.0, aka honeycomb, aka the tablet/landscape focused Android variant).

Which lead to the situation that although Windows Phone failed in the market, Windows 10 seems to be on good track to win the hybrid tablets market.

All the consumer stores on my city have mostly Windows 10 hybrid laptops on sale, with the exception of a few Samsung and Huawei ones with Android.

In particular as Microsoft has waved the license on smaller screens.

The other day i found a 10" tablet with a keyboard dock and no less than two A ports on the tablet part.

I am presently contemplating grabbing one to use with a RTLSDR dongle i picked up on a lark.

In android it works right now on the app toolbar with a long touch of a button for which you want to see the tooltip (if it is programmed right). The text shows up sort of like a toast message.

Devices with a stylus (like the Galaxy Note series) can use it by hovering on the element.

Speaking of the note series, I wonder if the note 8 will ship with Oreo and if so how well it keeps the treble stuff.

:(

The only place I can recall using tooltips (if I understand what you're referring to) on iOS is to read the extra caption on XCKD (the title attribute of the img element), which you access by press and hold.

Just put LineageOS on my Note 3 and it turns out the touch screen is sensitive enough to implement a "Touchscreen hovering" feature.

Dunno exactly what they are referring to, but on Fragment UIs one can tap and hold on buttons to get a small popup/tooltip.