Bear with me here since this can be a bit confusing:
You have SSD, M.2 and NVMe drives available these days when it comes to solid state drives (i.e. no moving parts). I’ll leave standard hard drives with a spinning disk out of it till a bit further down.
SSD usually refer to something that looks like this (about the size of a deck of cards and pretty thin). They have been around for a while and plug into a SATA connection on your motherboard (which these days they all have). They generally have better performance than spinning hard drives but there are pros and cons depending on purpose.
M.2 is a form factor change of the SSD mentioned above. It looks more like astick of gum in size and shape. This goes into a special slot on your motherboard (mobo) as you mentioned. It performs the same as the SSD mentioned above (just changed the shape and the connector). It is just smaller and goes in that special slot. These slots are very common on modern mobos these days but you’d need to check to be sure.
NVMe looks just like the M.2 above BUT it is different. NVMe has it own bus which is much faster. SATA was made using what old, spinning drives used. NVMe was made with SSD advantages in mind and it makes a big difference.
SATA-III maxes out at 600MB/s (real world will be somewhat less) transfer speed. NVMe can get you 3500MB/s. Waaay faster.
Remember M.2 is a form factor and a SATA version and an NVMe version look almost exactly alike. You need to read the specs on the mobo you buy to be sure what it takes.
So, which do you want?
Well, spinning drives are cheap for mass storage. NVMe is fast but expensive. You can do what you want but, usually, people use and NVMe (or SSD/M.2) as a boot drive. You can even make it a little bigger and use it as a gaming drive. You will not have a lot of storage for games but you can have a few on at a given time and swap them in and out as needed giving you great gaming performance.
For video/long term storage you want massive space that is cheap. That will probably be spinning drives. The manufacturers now make drives meant to be very long lasting and super reliable. They won’t last forever, nothing does, but they are good for this purpose. Here is the Western Digital page on them (just an example, their competition does similar things and are worth looking at).
SSDs wear out a bit faster than spinning drives do and are less suitable for massive I/O purposes (e.g. a video security system that is constantly writing to them).
I will leave it at that except to say RGB lighting is bling. Make your PC they way you want it to perform. After that, if you want the bling (and I get it, it can look pretty cool) then go for it. Getting LEDs in your system is all over the place from the memory to the CPU cooler to the video card to the case. It is a whole specialty unto itself.