A straightforward RSS for the mail client would be great. It's a simple, old school protocol so they shouldn't have to reinvent the wheel to implement it. Thunderbird has great options for how long or how many to keep that would be perfect for Proton to mimic. Hope we see it.

A simple RSS reader - no AI needed - that is also a standalone app with the ability to automatically download articles for offline reading. Reading habits are a wealth of data, and de-ai-ed/de-algorithmed news and feeds are likely important to many using Proton.
Would be easy to incorporate a free tier as well. Could also be bundled with the Mail app if that is more the speed of development.

I would gladly use a Proton RSS Reader. Thunderbird, Mozilla's email client, already has this feature (https://blog.thunderbird.net/2022/05/thunderbird-rss-feeds-guide-favorite-content-to-the-inbox/).

Proton already recognizes the usefulness of RSS feeds; they have one for their blog (https://proton.me/blog/feed).

When Proton advertised the blog on the r/ProtonMail subreddit they told us, "You can subscribe with your favorite RSS reader" (https://www.reddit.com/r/ProtonMail/comments/xuliqq/the_proton_blog_feed_is_back_online/).

Ever since Google shuttered Google Reader more than 10 years ago RSS readers have remained fairly niche tools. RSS readers do not have the same cultural prominence as say podcast players. Telling us to "subscribe with your favorite RSS reader" would be a far more useful instruction if Proton offered the tool themselves.

Proton is the company that boasts, "Privacy by default." RSS is decent at protecting privacy, allowing users in some ways to subvert surveillance measures by advertisers (https://www.anildash.com/2024/02/06/wherever-you-get-podcasts/).

I feel like it would be in all our interests' for Proton to include an RSS reader in its suite of products.