The free Mozilla Thunderbird email client has had this feature forever, it blocks remote images by default. It's nice to see Apple dipping a toe into the 21st Century.
The Apple Relay looks like a game changer at $1 a month. A VPN let you stream shows from England or Europe months to years ahead of when it is available in the US. An anonymous VPN like TorGuard will cost $10/month.
Apple Mail and Outlook, among others, have allowed blocking of all images or disabling HTML mail for a long while. If I understand what Apple is doing correctly, they will block the tracking but allow the formatting and non-tracking images.
The article mentions what Apple Relay blocks. It seems to amount to the same thing as a VPN service, but it appears to ignore traffic that is already going via https. Since the DNS is going through Apple Relay, that traffic is effectively obscured from the ISP. However, Apple Relay does not provide options for the geographic location of the exit node, so streaming from outside of the country likely will not be possible.
From the article:
What Traffic is Included in iCloud Private Relay?
An iCloud+ user running iOS 15, iPadOS15, or macOS Monterey with Private Relay enabled will have the following traffic routed through Private Relay:
All Safari browsing
All DNS queries
Most App Traffic to insecure websites (aka TCP Port 80, or “http:” traffic).
What’s not included in Private Relay?
Private Relay is bypassed for everything not listed above, including:
VPNs, Proxies, and other Network Extensions
Secure, “https:” traffic from your apps.