While Solano is my personal favorite, Jon Berti is right there with my next favorite utility infielder I would love the Mariners to try and acquire. He is the only name on this list that would require the Mariners to trade for, but he shouldn't be overly expensive considering he is almost 34 years old.
Berti was one of the more underrated players in 2023, playing 133 games, slashing .294/.344/.405 for a 103 wRC+. He stole 16 bases (though he stole 41 in 2022, showing elite base-stealing ability). He has also been worth 4.3 fWAR over the last two years. His strikeout and walk rates have been right in line with what the Mariners have been looking to add. Berti played the most games of his career in 2023 and has gotten better with more playing time.
Berti provides a lot of the same type of versatility that Dylan Moore does, albeit with more consistency and less strikeouts. Berti played 64 games at shortstop, 41 at third base, 18 in left field and 15 at second base. He gives you the same flexibility that Moore gives you, but more certainty, allowing you to play Moore versus lefties more specifically at second base with Rojas and letting Berti play more of an everyday utility role.
Finding a match here is sort of difficult. Berti doesn't have a ton of trade value with him being 34 years old and only under contract this year and next, but he has been a solid performer. With a new GM, I am not sure which direction the Marlins want to go. They could use some help in the outfield and maybe a shortstop, maybe Cade Marlowe gives them enough club control and upside to do it. Maybe you could swap Dylan Moore and a prospect for Berti; Moore is a few years young, both have a couple of years of control, but Dylan Moore can play some shortstop for the Marlins.