Reddit mentions of V8 Smartwatch Fitness Watch Wrist Phone Watch Touch Screen IP67 Waterproof Fitness Tracker with Heart Rate Monitor Pedometer Sports Activity Tracker Watch

I tried doing this for 30 minutes with /u/jonnyburger's technique below, using my portable bluetooth keyboard and a Pixel XL, and it's not that bad of an experience in landscape mode.

Here's a screenshot of what it looks like.

Get a little fold out bluetooth keyboard. They're pretty cheap, small when folded up, and if you are the kind of person who wants to do a lot of typing when on your phone/tablet they're quite handy. I have one that folds up to be the same size as my phone, and unfolds to be almost the size of a standard keyboard (If I line it up with the enter key it almost touches capslock and the width is almost identical to the distance from space bar to 7).

1byone foldable bluetooth keyboard

I've had this little rechargeable keyboard for several months with no issue: https://www.amazon.com/gp/product/B00VRCKK1Y/ But it's main draw for me is that it's portable and folds up. Folding is probably a drawback if you don't actually want that feature.

Then I have this thing which does take AAA batteries, but it's not mini: tps://www.amazon.com/gp/product/B00MUTWLW4/
I really like it, though. Can simultaneously pair with my phone, MiBox, and tablet just by rotating the little switch. But not really remote-sized if that's what you're going for.

Do you type in landscape on the phone screen? If not than maybe the link I posted would be better than nothing.

Also you could carry around this in your pocket: foldable Bluetooth keyboard

There was also a Kickstarter I believe for a slider keyboard that was attached with 3m tape to the back but I couldn't find it nor do I know if it was successful.

For me I can type just as quick as someone proficient at using a virtual keyboard with two thumbs while I swipe. I use Google keyboard which works really well for me with the auto correct turned on. If you want to try swiping start with typing all your small words and leaving larger words to pecking then eventually you'll slowly start typing every single word in it. Google's keyboard also will learn new words if you type them a couple times. It takes about a week to get the hang of it and see it's value and a few months to build muscle memory for the common words you type.