You can do this easily with zsh’s standard features. I love having years of my command history! It's all combined across sessions and instantly searchable with the standard ^R.

These are most of the settings in ZSH I use to enable all that.

  HISTSIZE=10000000
  SAVEHIST=10000000
 
  setopt EXTENDED_HISTORY # logs the start and elapsed time
  setopt INC_APPEND_HISTORY   
  setopt SHARE_HISTORY
  setopt HIST_IGNORE_DUPS     
  setopt HIST_IGNORE_ALL_DUPS
  setopt HIST_FIND_NO_DUPS

Apple now even recommends zsh shell over bash! =) https://support.apple.com/en-us/HT208050 (it's the 10.15 default)