you can install what ever you want and your wallet is available to ^^
i have now the 500GB Samsung EVO 970 M.2 NVMe with an adapter installed. more is possible.
M.2 NVMe is the cheapest way to upgrade your MacBook. If you have to much money, you can also buy an OWC SSD (up to 1000$ for 2TB; Samsung 2TB 500$)
after disconnect the battery, press and hold 5*10 seconds the powerbutton on your keyboard to unload the capacitors