I've had Samsung phones on Verizon for years and really didn't notice any bloatware. If there were games and things that I didn't use, I could delete them.
Now a friend of mine has a subsidized Samsung brand phone from WalMart (pre-paid) and that thing is loaded with stuff. Same goes for another Samsung branded phone through Spectrum (Comcast). On top of the advertisements, which are everywhere as pop ups, even on the home screen, they also sell your phone number! So sales calls become incessant.
You can't sell a phone with unlimited data/text/talk for $29.95/mo without selling ad space or your number.
Google is just about as bad now with their pop-ups.
I'd say most bloatware is carrier installed.