Makes me think of one of my favourite websites to spook my family/friends/colleagues into being smarter on the internet.
EDIT: they referenced it on the website, glad I don't make my living proof-reading things.
In another life looking into to the CS I liked a chap called Paul Cairney who wrote a book called "The politics of evidence-based public policymaking. It's 120 pages long and you can get is cheaper on eBay/Aberbooks, etc. He also had a blog post which gives the main arguments/points.
But yeah. Policymaking is messy, everyone makes shortcuts. So don't be a neurotic completionist and make priorities. Also develop a network inside and outside you can rely on for advice and expert opinion. Most will be pre-existing in your policy area, but if it's something new and emerging building/expanding a new network can help.
For practicalities How to be a Civil Servant by Martin Stanley is good. Other users linked his two websites which will probably be a substitute for the book (?).
As has been said, you’ll be fine if they’re in-ear or over-/on-ear headphones. So long as they’re plain in appearance you have nothing to worry about. Be they small white Apple earphones etc or large professional black/white/grey headphones/headset over your head, it doesn’t matter. That you can hear each other clearly without background noise is all that is important!
I had a remote (internal) interview last year (passed) and I used some decent black Sony headphones with this plugged in to it https://www.amazon.co.uk/V-MODA-BoomPro-Microphone-Gaming-Communication/dp/B00BJ17WKK/ and if anything, the superior quality and ability to block out background noise compared to the standard headset work provided made me perform better and be more concentrated on the interview.