On Switch there aren't that many good releases yet even if there's Yoku's Island was incredibly refreshing and Salt&Sanctuary which is coming. There's also Shantae and the pirate's curse which is great. I can't tell you for the monster boys because I haven't played them.
If you have a PC, there are plenty of stellar indie metroidvanias that didn't get as much attention as they would nowadays.
>Aquaria
>Environmental Station Alpha
>Valdis Story
>La-Mulana 1 and 2
>Rabi-Ribi
On emulator you can easily play the castlevanias
>Aria of Sorrow
>Circle of the Moon
>Harmony of Dissonance
For DS, there's
>Portrait of Ruin
>Down of Sorrow
>Order of Eclesia
Among the other less known metroidvanias, there's Kirby and labyrinth of mirrors which is incredibly refreshing.
Also, less traditionnaly "metroidvanias" there are
>Rain World which is an incredible 2D non linear platformer (super hard though)
>Teslagrad which has every elements of the metroidvanias but is a bit too railroaded.
>Cave Story which is the same