In a c64 emulator, full screen. You can find the .d64 floppy images online. Use a joystick or at least a cheap usb gamepad, the ship to ship fighting is more fun than.

Or if you have a real C64 with a CRT that would be best, but than with some kind of mass storage attached (anything that is faster than a 1541 since the game is so big it has to load before every fight or other activity).

The game can be pretty immersive and playing it through is a multiple hour endeavour.

If in a ship to ship fight, you gotta raise sails first (by moving the joystick up).

Edit: Vice is an emulator packaged in Debian Contrib, but you need the C64 ROM file (easy to find online).

"In a browser" is always an option:

https://archive.org/details/msdos_Sid_Meiers_Pirates_1987

https://archive.org/details/PiratesMacintosh

There are probably others, but Archive.org is misbehaving at the moment.

The Xbox remake from 2004 plays well on current-gen Xboxes.

I played the remake, which was pretty good, though now 20 years old itself.

tbh if you want to scratch the pirate-y itch, Assassin's Creed Black Flag is excellent, if just for the sea shanties.

Which has itself just had a remake released for it I see! I don't keep up with games these days.

The remake is on Steam

gog.com or Xbox backwards compatibility?