Train from Zurich Airport to Basel and Basel to Metz with "hop offs"

but it seems that all of the trains are for specific times I'd like to understand if I can buy a train ticket from the airport to Basel, hop off at the Zurich HB, and continue on to Basel without multiple tickets.

Yes you can. You're ticket is not tied to any specific train. The trains are mass transit. Everday people use them to go to work or school for example and public transportation systems (trains, buses, boats, airplanes) generally run on a schedule, so you know when to show up for your ride.

Trains are for specific times, for obvious reasons. But tickets are not. Tickets are by default for a route, so allow you to progress along that route on any train on the route, as long as you keep moving in the same direction, and finish before 5:00 the next day. So you can break in Zurich.
But that only applies to default tickets. Supersaver tickets (which are discounted) are indeed for a specific train. So you could for example buy a supersaver ticket Zurich HB to Basel for a train convenient for the time you want to be in Basel, and then just buy a Zurich Airport - Zurich HB ticket at the airport once you have exited customs.

How long are you staying? Would a half- fare card or Swiss Travel Pass be to your advantage?

We’ll only be in Basel 2 nights, so it doesn’t seem like a pass would be worth it, but please lmk if I’m missing something!

I think I’m finding a solution with the SBB Saver Day Pass. Anyone have experience using this?

Saver Day Pass gives you unlimited use on all public transit in Switzerland for a whole day. So if that is the cheapest offer available to you know by all means get it, as it allows you to go anywhere you want in Switzerland at your own discretion, and that for a whole day.

The Alsace also has passes that allow unlimted travel, See here: https://www.ter.sncf.com/grand-est/tarifs-cartes/tarifs-regionaux/alsa%2B-groupe-journee