I asked all of our friends to upload to a Google Photos shared album. Most of my friends use Android and most of my wife's friends use Apple-- didn't hear any complaints about Google Photos. Our experience was that most people have a google account anyways and are familiar enough with Google Photos.

The people I asked for advice said that they'd prefer to download Google Photos to upload/view photos vs. a third-party service that didn't require them to download anything (i.e. Synology photo request).

For Google Photos, make sure to set the "BACKUP QUALITY FOR PHOTOS & VIDEOS" option to "Original quality". It's the very top radio button under the settings (for my using Google Chrome on my laptop). Can't miss it.

I hadn't considered setting up two shared albums to meet people on their platform, so thanks for that idea!

One problem that I often encounter is that people either don't use Google Photos/iCloud, or they don't have sufficient free space in their cloud storage account to upload photos/videos. Additionally, in the case of Google Photos, if the person has configured Standard Quality for their personal account backup, the shared photos will not be in the original quality.

You might want to browse through this HN post about Google Drive losing data that's on the front page at the same time your AskHN is:

https://news.ycombinator.com/item?id=38431743

within the comments, there's people also complaining about losing photos as well. just so you're fully informed