This is the most dishonest comparison I've ever seen. The Surface Pro with OLED, 16GB RAM (twice the RAM of iPad Pro), and 512GB is $1349 on preorder right now (regular will be $1499). The iPad Pro with 8GB RAM and 512GB storage is $1299. To get 16 GB of RAM, you would need to get the 1TB iPad Pro model which is $1899. If you want the Surface Pro to match on RAM and storage, it would be $1529 on preorder or $1699 MSRP.
You could argue that there's not enough to do on iPad to warrant 16GB and that would be a sound argument.
You have a lot of options for keyboards and pens. You can use an old keyboard or pen from a previous Surface Pro. You can get the $279 keyboard with slim pen, the $139 keyboard, the $179 keyboard with pen storage, or the new flex keyboard and pen for $449, or the flex keyboard without pen for $349. And you have the old pens and third party pens as well.
The new magic keyboard for iPad Pro is $349 and it wobbles like crazy (see lots of Youtube videos). And the Pencil is $129. $349 + 129 = $478. Last time I checked, $478 is more than $449.