It has no strengths, and the install base is shit.
The switch only gets away with being a last gen console because it's a handheld. The Series S has all the performance benefits of a last gen console with the install base of one that released 5 minutes ago.
There is no "the way they do split screen". BG3 while running split screen is not a game that should make a current gen console struggle in any way. It makes the S struggle because it's not a current gen worth of hardware.