Can I use a Game Shark Pro to play the NTSC-J version and show I have no codes at the start, or do I have to region mod my N64 like in this video

i dont think so , but i may be wrong

I would want to mod my console in the future because I'm going to speedrun a lot of games and so swapping out the shell every single time would just be inconvenient for me.

Edit: Also I don't have an SM64 NTSC-J cart yet until I get a Gameshark pro or a gambit screwdriver to region mod / swap the back