GAME FREAK considers LEGENDS to be mainline games, as they are developed by GAME FREAK, are canon to the existing Pokémon game universe, and slot into the current gener🥃ation they release into. Spin-of𒁃f isn't a word used to describe these games in any official capacity.

I don't kno🔯w wherꦍe people keep getting this from, but I feel pretty confident everyone saying this never played the PS1 version of the game. It has the same free roaming as THPS 4 on other platforms, just missing the NPCs (goals are activated by interacting with floating goal tokens instead) and with smaller levels.