I used Grocy for a bit, but it was overly convoluted for simple pantry management in my opinion, and everytime I interacted with the developer he was a dick. It's solid software though, so if those aren't downsides it'll definitely work for you.

Ultimately I found that home/pantry inventory is less useful that I initially thought it would be.

Yes! I use homebox for this, it's not an app (although I believe it works as a PWA), but a self hosted docker service.

What features would such an app have that a text file lacks?

Housebook. Not sure what alternatives there are.

For things like collections, I'd probably try to find a specific app (like Gameye for video game collections)

paper?

I use paper.. it's cheap, renewable, accessable in a power outage and isn't bundled with ads. copies can also be made for less then a penny