I just assume you are in the US and i can’t speak for the situation there. Here in the EU there are plenty of options. Sure it’s a bit more expensive sometimes, but often times it’s not.

And the convenience, I get it. Amazon customer support is unbeatable. From what I hear it is getting worse, though.

For me in the EU it is possible, but sometimes a struggle. The ideological thing makes it worth it for me, and if there are more and more people that don’t use Amazon (as often), there may be a time when it dies.

The only items I bought on Amazon since coronavirus hit are a phone charger, some shirts that aren’t available anywhere else and a pedal for a sewing machine.

So I can’t tell you ~~an alternative~~ the alternative you are looking for, but for me it is a lot of small to large online stores and some offline stores as well. There isn’t quite something as convenient that has virtually everything out there, afaik.