One-finger keyboards for Esperanto, English, and Russian

Decades into the smartphone era, seven billion people communicate with one finger on a virtual QWERTY keyboard. Why not arrange the keys for one-finger typing, with the spacebar and most common letters in the center? Jean Ichbiah did that in 1995 with his FITALY keyboard, and no one noticed.

Here are my arrangements:

On the left is Ichbiah's FITALY, to which I've added digits, symbols, and Esperanto diacritics. If you don't use Esperanto, you can fill those seven slots with whatever you like. A long press on a letter gives the symbol below it; feel free to add symbols under the digits and bottom-row letters.

On the right, I've tried to create something similar for Russian. I calculated, for billions of permutations, how far a finger would need to travel to type the complete text of Anna Karenina. In fact there are 263 decillion (2.63×10³⁵) permutations of 32 letters, so mine might not be ideal, but it looks pretty good.

With digits, I put 1, 2, and 3 nearest to the spacebar because 30% of numerals in documents start with 1 and another 30% with 2 or 3, according to the Newcomb–Benford law.

You can use these layouts for free on your Android device. Go to Google Play and install Multiling O. Hold a finger on the spacebar, drag it to Layouts, choose [ + DIY ], and paste the following text:

{
"title":"62FITALY",
"onScreen":{
"main":[
"84zvchwk[DEL]",
"62fitaly[ENTER]",
"01[SPACE][]ne[SPACE][][SHIFT]",
"73gdorsb[SYM:,]",
"95qjumpx[ALTGR:.]",
"[TOOL] ĵŝĉĝŭĥ[FDEL]"
],"sym":[
"  #$_-+= ",
"  %&<>/* ",
"  ³²()÷× ",
"  '\"[]\\@ ",
"  `^{}|~ ",
"" ] } }

{
"title":"62RUSSIAN",
"onScreen":{
"main":[
"84цздмуж[DEL]",
"62ылаикч[ENTER]",
"01[SPACE][]не[SPACE][][SHIFT]",
"73бвотся[SYM:,]",
"95хгрпьй[ALTGR:.]",
"[TOOL]ъёщшюэф[FDEL]"
],"sym":[
"  #$_-+= ",
"  %&<>/* ",
"  ³²()÷× ",
"  '\"[]\\@ ",
"  `^{}|~ ",
"" ] } }