Regarding the original question what I purchased to get B/Ks: nothing. Absolutely nothing. However, when I spoke to the SAs they would know that I knew H products well, from mentioning all the colors and leathers that I love.
I have a K32, B40 and B35 - all purchased from H boutiques around the world.
I got on the waitlist for the K32 (black box GHW, retourne) without the SA knowing that I purchased a belt and a perfume from someone else before at that store (and they don't ask for your ID to keep track).
For the B40 (my very first B) I was a walk-in tourist at a store on another continent. Never went there before this one trip, let alone buy anything. I went 3 times within 2 weeks and got to speak to really nice SAs who referred me to someone in the leather department. On the day before my departure I finally met the SA and got very lucky.
For the B35 (my dream colour and combo) the hotel concierge arranged an appointment at FSH (was in 2017). Was also lucky to have a great SA who showed me the B35 in Bleu Paon (a colour I wanted for more than 5 years) and I was able to purchase it without anything else. I did purchase 3 leather bracelets in France in the years before. But again, no ID as I'm not eligible for tax refunds anyway. And the appointment was not even in my name (in my friend's name, who was not an H client before). So H/the SA couldn't have known about my small purchase history in France.
I did and still buy various H items I really want. But always at whichever place happens to have it (including h.com), never to build a history. So to the question what else I enjoy from H: SLGs like the Ulysse GM, MM, PM, Calvi, Vision Agenda (basically had to collect colors I love), scarves, perfume, jewelry, leather bracelets, other bags (Evie, Medor clutch).