Why few navies copied the pocket battleship

Did any other navy build a pocket battleship as the capital ship of a force that had nothing better?

Not really; the design needs an unusual combination of capital-ship industry and a political or treaty reason not to build a true capital ship.

A pocket battleship requires a navy large and industrially capable enough to build a capital-style gun system, yet unwilling or forbidden to build a normal capital ship. Most states in that position could instead choose a proper battleship or a more balanced cruiser. Combining capital-ship guns, cruiser range, and modest displacement forces severe compromises in armor, speed, or machinery. The Deutschland class therefore reflects an unusual treaty circumstance rather than a pattern other navies had strong reasons to copy.