In one of my best sales jobs, I got a full day training course on choice fatigue and how to guide customers to both maximize revenues and their happiness. The business I worked for had high rates of customer return, so the training was centered not around scalping the most money today but how to develop a lifetime relationship where we maximize LTV.
It was pretty fascinating. I ended up doing a fair bit of independent research on the topic to see if it was just same sales BS or a known psychological phenomenon, and it turns out it's a well-known branch of psychology/sociology. (Not necessarily related to the Decision Fatigue / Ego Depletion theory which has been tough to replicate, but is probably true in some respect).
Coincidentally enough, I took that education to my next job, which was waiting tables, and it held up there very well. The key, in my opinion, is actually being deeply knowledgeable about the product so your recommendations are authentic. Bonus points if you use the product.