systemd-run --unit=firefox --user --scope -p MemoryHigh=8G -p MemoryMax=9G -p MemorySwapMax=1G firefox

sysmemwatch firefox

firefox:  31%|█████████            | 3024007/9663676

sysmemwatch -l -t 30 firefox vscode studio

syswatchmem -- utility for see the memory of each scope launched with systemd-run

Usage:
  syswatchmem  <scope>... 
  syswatchmem [--loop] [--no-stats] [--anim <tics>] [--time <delay>] <scope>...
  syswatchmem -h | --help
  syswatchmem -v | --version

Examples:
  syswatchmem -n firefox                # watch the memory of firefox one time without stats only %
  syswatchmem -l -t 60 firefox vscode   # loop mode: watch the memory of firefox and vscode each 60 seconds
  syswatchmem -a 5000 firefox vscode    # animate more the memory bars (minus is more slow)

Options:
  -l, --loop                    Loop forever
  -t <delay>, --time <delay>    Time between updates [default: 30] seconds
  -a <tics>, --anim <tics>      Anim speed [default: 10000] minus is slower
  -n, --no-stats                Disable statistics
  -h --help                     Show help screen.
  -v --version                  Show version.