So the basic concept here is to:

• Collect total pageviews of [[Help:IPA]] across all wikis (https://www.wikidata.org/wiki/Q1229525)
• Collect total mediarequests of files used by [[Template:IPA_audio_link]] across all wikis (https://www.wikidata.org/wiki/Q8140322)
  • This may require parsing the wikitext to determine which file is being linked

Relevant APIs:

• To get sitelinks of a page from Wikidata: action=wbgetentities with props=sitelinks
• To get tranclusions of a template: prop=transcludedin
• To get pageviews of a page: prop=pageviews or RESTBase /metrics/pageviews/per-article
• To get mediarequests of a file: RESTBase /metrics/mediarequests/per-file

Using the above APIs, you'd write a script to loop through to sum all the data for a given date range (say, the past month).

Could this also use https://meta.wikimedia.org/wiki/Research:Wikipedia_clickstream to find the articles where users ended up at [[Help:IPA]]?

Could this also use https://meta.wikimedia.org/wiki/Research:Wikipedia_clickstream to find the articles where users ended up at [[Help:IPA]]?

That data is only available for the mainspace, I believe.

Pageviews on Help:IPA and subpages for all wikis in the last 30 days.
Grand Total is 1,758,387 across all projects.

Here is the list of all projects and sub-pages that had 1 or more pageviews

I've manually verified a couple via massviews and it is fairly close (it is never gonna be the same 'cause massviews uses restapi and I'm using the action api)

Further to the above, I ran a query to see how many transclusions of IPA templates there are that don't have community-recorded audio already:

SELECT COUNT(*)
FROM templatelinks
WHERE tl_title LIKE "IPA-%"
  AND tl_title NOT LIKE "%/%"
  AND tl_namespace = 10

which comes out to 124,854; minus the 17,858 with audio already (by counting at transclusions of Template:IPA audio link) we have 107,269 possible audio files. This data is just for English Wikipedia.

Using @dmaza's data, and not including @MusikAnimal's, it looks like the total is going to be in the realm of ~1,758,387 views in the last 30 days