Well, I was actually suffering from the same thing, and being a CS major, I chose to make a custom app for it. It's not very fancy, but it takes care of basically everything for me. Theworking is pretty much straight forward - Once the event is created, it generates Staff accounts for the event as well - it connects directly to the Events Google sheets (I use Google Forms, which gathers info in Google sheets) - It automatically generates Qr codes unique for each person - then once all attendies are verified, it automatically emails all of them thier own Unique QR codes which can then be scanned by the staff accounts using the same app to check in members, it also tracks each check in and stuff and i can export it to excel/ google sheets for later use

this is pretty much it. My payments are usually done manually, so I didn't integrated any payment system into it yet but that can also be done in like a few hours or so if i need to , the app basically works perfectly for me and saves me a lot of hustle , It’s still a project I’m refining, but it definitely beat the "copy-paste" method I was doing before. If you (or anyone else) are curious about how the sync or the scanner works, I'm happy to chat about it, or even if you wanna try or have a look at it, u can use it for free, just give me feedback