Yes, I am afraid that is your only solution if you want to use Linux.
Get as good a card as you can afford.
Make sure the PSU in your machine is adequate for your chosen card.
Stay away from Nvidia… choose AMD or Intel
“probably RX6400 4GB DDR6”
At least I can confirm that one works with every Linux I have … MX, Void, Devuan, Artix, Antix.