Historically, very few tablet computers have come with the specially polarised LCDs which are sunlight readable.
Plenty of ruggedised tablets have these screens (do a google on "ruggedised tablet") but they tend to be very heavy - 3kg is not unusual. The widely used Xplore IX104 is one example - almost unusable in the cockpit due to weight and heat generation. Tablet technology lags years behind laptop technology and little effort has been made to make them lightweight. Most tablets, when you dismantle them, are just metal boxes with a traditional small PC motherboard inside; nothing clever at all.
The LS800 is one of the few tablets with the sunlight readable screen, which is also not too big and heavy. However it is now discontinued so it's Ebay etc.
The mfg (
Motion) seems to be going after weird medical markets now.
I suspect the general-purpose tablet market is going to collapse, like the PDA market has done, but the big (12") tablets might remain, but they are too big for cockpit use.