I would say that's uncharacteristic of typical Meraki presentations, which are usually the opposite, much less slides and much more demo. Then again, depending on who was in the audience (always a mix) you may have some highly experienced Meraki customers, some who have never even heard of Meraki or seen Dashboard, and all other levels in between. I've given plenty of presos to larger groups where it was tough to strike a good balance of sales pitch versus technical depth, and beginner versus advanced levels. I (and most audiences) much prefer to talk less to slides about what we CAN do, and spend more time in live demos showing and explaining how we actually do it on a live network. Then again, SD-WAN can get a bit involved, so certainly some slides and background is in order. Maybe what you ended up was more of an overview of the MX platform with just a few minutes demo on SD-WAN. Sorry to hear that was a bummer and came off too salesy.
Anyway, keep in mind you can also engage with your local Meraki field reps (or their inside rep counterparts) to arrange a Meraki Minilab event, and we do have hands on labs specific to SD-WAN among many others. Perhaps that is one option to only get a handful of technical-only slides followed by hands on labs on a variety of topics including SD-WAN.
Also, you may have seen it, and it might be a little higher level, but there is a webinar from Meraki's webinar series that was focused on SD-WAN (first 20 minutes is MX overview, the rest is SD-WAN):
https://www.youtube.com/watch?v=zRgIMaNZDlY