I can't speak for this CEO, but if I were in the position I think I would get more value out of you being a silent shadow, and then debriefing you and getting a fresh perspective on the operational aspects of the organization.

If my goal was truly to observe the CEO and learn from him, my approach would be to be as silent and 'small' as possible - don't speak, don't draw attention to myself, sit behind the table, not at it, etc. I'd want everyone --including the CEO-- to forget I was even there.

I suggest you need to figure out what your goal truly is: to learn from him, or to 'bring value' for some reason? I'm not sure the two are compatible.

Taking a role in meetings could potentially create a lot of awkward power dynamics between you and the other executives, in my opinion.

Also, not to doubt your skills, but someone who doesn't have experience in the space "offering to help on sales calls" probably would be a net detriment.

Have a great time!

One that worked for me was to listen carefully for some opportunity where I could help. Like, "it sounds like you're negotiating with Microsoft... I just finished doing that with another company, there may be some helpful things I could share..."

Something like that creates a basis for an ongoing relationship. Such that you don't have to try to press a sales pitch in a hurry.