It depends on what you're using for the resolver.
I'm assuming you only care about gethostbyname(3) and friends. With glibc that means nss; generally you're also looking at libnss_dns.so, which uses glibc's resolv (copied from BIND). This doesn't include enough configuration to do what you suggest; it pretty much just points everything towards a server.
So you have two options: use a different NSS module (maybe write your own?) or have a proxy DNS resolver that sends different requests to different places.
systemd-resolved actually handles the first option pretty well (although it would prefer that you use the dbus interface over gai). It can handle multiple interfaces with separate domains and split DNS fairly well! (Not so good with reverse DNS, unfortunately. But I get it, reverse DNS is pretty hacky anyways.)
If you prefer the forwarder route, dnsmasq seems to be fairly popular these days in the embedded world and elsewhere.
If I were you, I think I'd write a short NSS module or use dnsmasq, depending upon your needs.
The better analogy in this case would be to an AmazonBasics USB cable, not to a phone charger.
Are there issues when anyone can provide a product? Yes. But this would certainly not involve Amazon opening the storefront to allow selling any sort of drugs, but rather them sourcing generic product themselves and selling it as private label.
I would have no problems trusting this product to be genuine, just as I have no problems trusting their other private label products. It's a different sort of issue.
I'm deeply saddened to hear that the Seattle Mystery Bookshop is closing. This feels like something easily missed in today's automation-based economy; the ability to go to an expert and get quality recommendations is not to be missed. Seattle Mystery Bookshop was only one of many excellent book stores in the Seattle area, but it seems that their number is diminishing by the day. I can only assume that that trend holds firm in other cities, and we are the poorer for it.
So you have two options: use a different NSS module (maybe write your own?) or have a proxy DNS resolver that sends different requests to different places.
systemd-resolved actually handles the first option pretty well (although it would prefer that you use the dbus interface over gai). It can handle multiple interfaces with separate domains and split DNS fairly well! (Not so good with reverse DNS, unfortunately. But I get it, reverse DNS is pretty hacky anyways.)
If you prefer the forwarder route, dnsmasq seems to be fairly popular these days in the embedded world and elsewhere.
If I were you, I think I'd write a short NSS module or use dnsmasq, depending upon your needs.