Check out one of the privacy-focused Firefox forks like LibreWolf, IceCat, or Waterfox. All three disable/rip out pocket by default, I believe, and reduce number of situations they phone home to Mozilla or Google. Memory savings are minimal though.
Librewolf is one of the more prominent ones these days. There's also Waterfox, which is based on an ESR (so, older) version of Firefox and likewise fits the bill.