First of all, welcome to this forum
Secondly and more importantly, congratulations on your upcoming wedding anniversary
Thirdly and even more important, a huge congratulations to your husband fir having married such a thoughtful partner that goes at great length trying to find the perfect gift.
As to your question what to buy; I’m no Patek expert but I would (in general terms) suggest two options: either buy a vintage model from the year you got married, or buy a model from this year in which you’re celebrating.
Given the fact that you, as you mentioned, are rather new to the world of watches, I would suggest to stay away from vintage watches. Too many sharks out there.
Once again welcome and please do let us know in due course what you selected
Happy days