Thank you for sharing the updates via this excellent article: "Custom Domains, Mobile Editor, and a True Following Feed".

Below is Just User's Suggestions,

[reference, newsletter, dated 15Sept 2022: "... Medium's new CEO Tony Stubblebine and product lead Breana Jones wrote recently, we want to build Medium in public with you. ..."]

First, on Medium Publications:

It will be very good and useful if rich formatting also available on the "Note from the editor" in the About Us section of publications. Many may like to use this section to write publication's guidelines for the authors and hence need text rich formatting [similar to what is available in Medium stories]

Reference Link:

https://fdiindia.bengalbusiness.net/about

And is there a way to automatically List all the publications in the profile of the Editor?

Now, auto listing of publications in the Editor's Profile is limited to 5 (five) publications; it's better if it is 7 (seven).

Next, Medium Partnership to promote Paid Membership:

Will PayPal be included in Medium Partnership programs?

Guess, "PayPal may be easily included in Medium Partnership program" by separating "Medium Partnership" in two categories:

1st one for promoting paid Medium membership,

2nd one for writing articles on Medium.

There may be other better ways to include PayPal in Medium Partnership programs .

Why do I suggest this? -- Because:

Medium needs more and more Paying Readers; and "Medium Partnership to promote Paid Membership" is (I guess) very important for Medium's growth and profitability.

So, a "widely accepted payment medium like PayPal" can be a very useful first step for Medium's next stage growth.

In my opinion, "Stripe only Policy" for Medium Partnership is a bottleneck for growth of Medium and Medium's profit.

Because Stripe does not work in many countries [with Billions of People] where Medium has high growth potential.

While, PayPal is more widely accepted in those countries.

Finally For now,

Is there a way to embed Medium Subscription Link on WordPress, email, newsletters [to be sent via Medium], etc.

Medium has many untapped potential for growth.