My son is almost 2 and has been an extremely unsettled & restless sleeper since birth. He’s still in a cot but wakes frequently often from rolling around and hitting the sides of the cot. It’s almost as if the cot isn’t big enough and sometimes we transfer him to a mattress on the floor. He sleeps in a sleep suit with legs. Is it safe to use a cot bumper now to soften the sides to see if that will help? Is a weighted blanket a possibility at this age?

Maybe this would be the time to move your toddler to a bed.
The following are the options to consider:
Floor mattress
Toddler bed
Adult height bed (You may also want to consider bed rails)
https://rednose.org.au/article/where-to-sleep-a-child-who-has-moved-from-a-cot

If moving a child to a bed, consider the safety aspects around your home
https://rednose.org.au/article/making-your-home-safe-before-moving-a-child-from-a-cot-to-a-bed

You may also find our cot to bed brochure helpful.
Download Cot to Bed Safety Brochure

There is mixed information about weighted blankets, but it seems that they are mostly not recommended for pre-school age children.

Red Nose recommends to use light weight blankets, tucked in tightly. for babies & young children.
If blankets are being used instead of a sleeping bag, it is recommended to place baby with his or her feet at the bottom of the cot, using layers of lightweight blankets that can be added or removed easily according to the room temperature. Tuck blankets in firmly so they cannot become loose and cover baby’s head during sleep.

https://rednose.org.au/article/how-much-bedding-does-baby-need