https://tunnelbroker.net/ will give you a free IPv6 subnet and you can route it over your existing IPv4 link. I think you can get either a /64 or /48.
Any request to a CDN will be slower since you’re not hitting the cache closest to your actual ISP, and since it’s “a VPN” a lot of things start to break, need more captchas, or get blocked for you since there’s a higher level of abuse from HE’s tunnel broker IP blocks.
I’m guessing they have larger blocks for sale?