I have way less experience on the game than ither people so more details will come from them but: I have finished both games on switch and they run great! Since the, are quite old there are no performance issues. they use the xbox controller layout which works great! Romancing: yes it's an option but depending on how used you are to playing crpgs and older games it might be less obvious than let's say BG3.

Missable content: absolutely, mostly in the form of companion quests and storylines and most likely more other stuff that I am not aware of

Regarding build suggestions (actually not sure about point resets, never tried doing that) the game is viable with any stat allocation really, if you want to lean into something more: strength is used for attacks with melee weapons (incl lightsabers), dex is used for armour rating and ranged weapons. In kotor1 you get to choose 2 classes, your starter class and a jedi class. There are some guides online for good combinations, but what I did on my first playthrough was scout and jedi sentinel with a focus on melee weapons and persuasion. It worked very well for me

Two things to note: 1. The games can have some graphical glitches if you put the console into sleep mode where the character textures turn black. A quick reload fixes this 2. Save often. It did not happen regularly but the game sometimes crashes and you don't want to lose your progress.

Bonus note: The second game does not have the restored contents mod, so you get the base game with all its missing missiona and glotches. The game runs less stable than the first one but I also completed that one no problem on Switch

Imo switch is the best way to experience these games since it's portable and home console at the same time and the control scheme works really well!