Is it possible to play any of his games without owning a Sony PlayStation ?
The first Metal Gear is available in English on the Nintendo Entertainment System. Not sure about the MSX2 version. It's also included in the Gamecube release of MGS.
No official English release for Metal Gear 2 on the MSX2. Fan translations available.
Many of the Metal Gear Solid games have had re-releases on the Xbox 360, and Windows ports in some cases.
Snatcher is on the Sega CD and Sega Saturn.
Policenauts, Saturn and 3DO.
He's had less-involved roles in a lot of games on other platforms, like the Gameboy Advance (e.g. Boktai, for which he served in producer and designer roles)
The first metal gear available on the NES has not much to do with the real first metal gear game, Hideo Kojima was not really involved in that adaptation for the NES, so it isn't considered canon or anything.
If I had to pick a platform for the full experience, that'd be the PS3 and the Legacy Collection bundle, which also includes MGS4 (physical BDD) and MGS1 as a digital download, I'm not sure if it's still available, but when it was, it was a great bundle.
Honestly though, it doesn't hold up well, and even as revolutionary as it was for it's time the dialogue was still often cringy.
I consider the gameplay to be superior, but it might not be worth it when it ruins the game's storytelling.