That Vintage Program grind looks harmless at first, then the Immortal PXP mission pops up and everyone starts checking old lineups while trying not to burn through MLB The Show 26 stubs on the wrong card.
The confusing bit is that MLB The Show 26 doesn't seem to treat Immortals like a clean modern card series. From what players are seeing, the mission is more about identity. If a player had an Immortal item back in MLB The Show 18, a current card of that player may be the thing the tracker wants. Not elegant, I know. You can stare at filters all night and still not find a neat Immortal button. That's why people are testing names after one game instead of trusting the menu.
I'd treat this program like a stack, not a single chore. Load Vintage cards where you can, then slide in likely Immortal names around them. That way hits, total bases, runs, homers, strikeouts, general PXP, and Vintage PXP all move at once. The Vintage path has no Moments, so yeah, it's more of a lunch-pail grind. The good news is you don't need to overthink every slot. A strong roster still clears the normal stat missions while your special cards chip away at the bonus ones.
Let's be real here: if the tracker does not move after one game, stop grinding that card immediately.
The safer pool starts with players repeatedly tied to MLB 18 Immortals: Ken Griffey Jr., Babe Ruth, Albert Pujols, Mike Trout, Mike Piazza, Chipper Jones, Ted Williams, Vladimir Guerrero, Rich Gossage, Bob Gibson, and Jackie Robinson. Yogi Berra shows up in ShowZone's visible Immortal data, which makes him interesting, even if some guide lists miss him. Then there's the messy group: Ryne Sandberg, Cal Ripken Jr., Dennis Eckersley, Tom Seaver, and Bob Feller. Some players swear by them. Others say they were Career Arc or didn't track.
Use the first game as a test, not a commitment. Once progress moves, grind hard with that same group, then decide whether market help or cheap MLB The Show 26 stubs makes sense for filling gaps.