Replacing light switch with motion sensor switch
There are not too many whites!  All those whites have a job. They are &quot;working for a living&quot;.  You do need to add your switch's neutral wire to that bundle. Do so competently. All the whites must still be connected to each other when you are done!
The red wires are probably the other half of a multi-wire branch circuit. This is a serious complication.  Because the black?Blue? wire will be on one circuit breaker, the reds will be on another breaker, and you must turn them both off in order to safely separate the neutrals.

In fact, Code now requires those 2 breakers be handle-tied so they must be shut off together. (for this very reason).  If you're lucky, they're already that way.  Otherwise you will need to do the &quot;legwork&quot; to identify the red breaker and assure it is off, before separating the neutrals. Once you've done that, either acquire a correct handle-tie, or get a 2-pole (NOT A DUPLEX) breaker (whose handles will be tied from the factory) and replace both breakers with that. Note the 2-pole breaker will take the same amount of room in the panel as both old breakers.

The new switch will care very much which wire is the supply from panel and which is  the onward wire to the light.  In your box, one is black and one is blue.  It's legal both ways, so we don't know what the installer did.  Regardless, it is safe to experiment here: simply connect them black-black and red-blue. If that doesn't work, swap them.
You must wire a ground wire to this switch, as Patrick discusses.  That is because the mounting screws can't make contact with the junction box through that wood-like material.  In fact, you can't have burnable wood-like material like that be a &quot;sleeve&quot; for a junction box!  That needs to be notched out (e.g. with an oscillating saw, those things are amazing lol) to fit either a box sleeve, or better, a steel box extension.  That needs to be done everywhere that is like that.  Otherwise a wiring problem in the box couls start a fire!