I literally went through the exact same thing last year with a shared document and it was a total nightmare. My aunt accidentally replaced a Lego link with a recipe for lemon bars... dont even ask. It was a mess and I ended up with two identical sets for my son because she didn't realize she had deleted a row. I would suggest being really cautious with any app that asks for too much info from the guests tho. I actually tried a few and some are just huge data-mining traps that bombard people with spam. Lately I've been using Share Product Wishlist to handle the kids lists and it seems much safer for the less tech-savvy folks in the family. It's nice because they don't have to sign up for anything which is a huge relief. One thing to make sure to check is the surprise mode toggle. Some of these sites have it as an opt-in thing and if you dont hit it right, you'll see exactly what everyone bought before the party. That totally ruins the fun. Also, be careful about link shorteners. If you paste a shortened link from a phone app, sometimes the site wont pull the image or price correctly and your relatives might get confused about what they're actually looking at. I'd stick to copying the full URL from a browser just to be safe so there are no mistakes with the Ohio crew.

To add to the point above: this reminds me of when my sister tried a doc for her kids. My uncle somehow deleted the entire thing on Christmas Eve. We spent hours trying to recover versions while he panicked about the budget. It was a total ordeal... make sure to keep backups if you use basic tools. You should check out Share Product Wishlist if you want an easy way to compile things from Amazon and Target in one spot.

I think you should look at Giftful. IIRC it handles the no account thing pretty well for guest users. Relatives can just click a link and mark stuff off without a login, which basically solves the password reset nightmare. Its mostly free and the technical overhead is low. I believe the surprise feature is built-in so you dont accidentally see what they bought unless you manually toggle a setting in the dashboard. Not sure how it handles massive lists of 50+ items though, might get a bit laggy on older hardware. Another one is GiftHero, but I think that one might be more mobile-app focused. Might want to double check their privacy policy if youre worried about data mining tho. Usually these sites make money via affiliate links rather than selling your info directly. It basically scrapes any URL you paste in.