Where to present the poll on the page

As @srodlund wrote in T248892#6112862, probably some folks don't scroll to the bottom of longer pages to spot that (currently defunct) gadget; UX input would be needed (would an overlay floating at the bottom be acceptable? probably not on mobile). T248892#6112912 also implied it wasn't displayed on mobile IIUC.

How to enable the poll on a per-page basis

Looking at https://wikitech.wikimedia.org/wiki/MediaWiki:Gadget-userfeedback.js , currently it is only on a namespace level.
I guess there could also be code to allow a manual list of pageNames instead, though I'd wonder about its performance at some point.

Evaluate our ability to include the poll on all key docs wikis

Stating the obvious, deploying some gadget is trivial in itself. Ideally a gadget has one canonical codebase location (when no per-wiki customizations are needed), and on other wikis the "gadget" would be a single line mw.loader.loading from the canonical location (until T121470 / Gadgets-2.0 happens; and as we have CORS).
But... if we wanted to display on a per-page basis (see above), page names will differ per wiki.
Maybe window.location.hostname could be checked, and used to be able to keep the list of pages still centralized in one place (basically: if on site X, then show gadget on pages A,B,C; else if on site Y, then show gadget on pages D,E,F)?

Process for collecting and analyzing the data

Related is the aspect of data retention for 90 days only, which makes identifying long-term trends and evaluation harder.

I also failed to find any docs so far how to visualize EventLogging data without reinventing wheels (and I learned that EventLogging does not feed into Logstash).

Probably not too helpful: A few weeks ago I went to visitporvoo.fi. At the bottom their form had three options; text could be submitted when not selecting "Yes"):