Great question — answering as the UphillTech team:
Answering my own question. Yes, in my case it is feasible to use the portfolio site as the canonical page in all individual gallery sites. I first attempted getting individual pages indexed, but failed. So I set the canonical url of each individual gallery to the portfolio/overview site, and I also added some short descriptions there. Now either the portfolio/overview or the individual site (not sure why) is often on the first page of search results when searching wedding [location] .
Full answer by S. G.: https://webmasters.stackexchange.com/a/141257 (CC BY-SA 4.0).
Need it done for your business? UphillTech.