Based on an idea posted on reddit by Flaky_Candy_6232:
https://www.reddit.com/r/neovim/comments/xij4yn/how_to_configure_undo_the_way_android_studios
Simply use your favorite plugin manager to install it, for example:
Plug 'EtiamNullam/gradual-undo.nvim'...then call:
require('gradual-undo').setup()...to load with default configuration, which will override u and <c-r> in normal mode.
Map to your own keys of choice or invoke manually by:
local gradual_undo = require('gradual-undo')
gradual_undo.jump_to_last_undo_position_or_undo()
gradual_undo.jump_to_last_redo_position_or_redo()