First off, if you're concerned about ISPs selling your data (couldn't exactly tell if that's a part of your concern), switching to private DNS provider and enabling DNS over HTTPS/TLS can significantly cut down on that, since most of what ISPs sell comes from DNS requests. That being said, they can still tell what sites you visit if you don't use a VPN/Tor, but they're less likely to care unless you're doing something illegal.
In terms of your obfuscation plan, I'm not sure that'd do much; if anything, it'd make you stand out more. A bunch of random traffic, even tweaked to fit your browsing habits, probably would look suspicious on their end and it wouldn't actually hide or disguise anything.
So ideally, you're just going to want to figure something out to set up some sort of VPN at some point. Switching DNS providers might be a bit of help in reducing sale of your traffic data, however. My recommendation is Quad9 but any privacy-friendly provider is fine.