Installing a home L2 charger before my next car purchase -- do I actually need to worry about J1772 vs NACS or am I overthinking this?

You're overthinking it. Get the plain J1772 unit. If you end up with a NACS car you put the adapter on the end of the cable and never take it off. At home it is the easiest place to use an adapter.

For AC this really is about as close to a non-issue as it gets. J1772 and NACS do the same thing at L2, so the adapter for a NACS car on a J1772 cable is basically just a shape change. Pins in, pins out. That's nothing like the DC adapters you read horror stories about. The swappable head stuff is solving a problem that doesn't really exist for home. The thing I'd be more careful about is going the other direction. Some Tesla EVSEs don't behave like a normal J1772 EVSE, so don't assume any random Tesla unit will work fine with a non-Tesla car through an adapter. The Universal is fine on that front, it was designed for both. But you don't need it Honestly the whole plug argument is kind of silly. Europe mostly figured this out with bring your own cable at public stations and nobody there argues about it. At home the plug on the end of your cable is the least permanent part of the install. The wire in the wall is the part that's actually a pain to change, so size that for more than you think you need

Agree it's mostly a non-issue at home -- the adapter just lives on the cable. I'd check what rebates your utility has before deciding though. When I was shopping some of the rebates only covered specific listed units, and that ended up mattering more to me than the connector.

I run a CCS1 to CHAdeMO adapter on my Leaf for DC fast charging and it handles that fine, so a passive L2 adapter at home is nothing. Just don't buy the cheapest one you can find. Get one that locks with a click and fits snug. A loose adapter is where you get heat.

Most home units here are tethered too, though. Bring your own cable is mostly a public charging thing. At home people just pick the plug their car uses, same as you would.

Ok this is reassuring. The Universal was about $200 more than the J1772 unit I was looking at, so I'll probably skip it. Dumb question though, if I get a NACS car does it come with the adapter or is that something I'd have to buy separately?

Depends on the brand and the year. Some include it, some don't anymore. They're cheap either way.

Whether you have to buy it separately depends on the manufacturer, and some of them have quietly stopped including it. Either way, buy one when you get the car and keep it in the car. You'll need it at some point, and it's better to have it than to go looking for one when you do.

I'd push back a little. We had a Tesla and a J1772 car at the same time for a while and the adapter kept ending up in the wrong car's frunk. More than once somebody got home and couldn't plug in. Sounds silly but it happened. One car? Adapter is fine. If there's any chance of two EVs in the garage, the extra $200 for the Universal is not crazy.

That's fair... though if it's living on the home cable it shouldn't be wandering off in the first place. Ours would have, I'm sure.

If the adapter keeps ending up in the wrong car, buy a second adapter. One lives on the wall unit and one lives in the car. That's still cheaper than the $200 difference, and you'd want one in the car anyway for destination chargers.

We had a MYLR and an R1S at the same time for about a year. Adapter lived on the wall charger the whole time and never moved. Not worth $200.

On whether the adapter comes with the car: GM shipped NACS adapters with the Optiq for a while. My mother's came with one, but it's a DC adapter and it has nothing to do with home charging. Read what's actually in the box before you assume you're covered. The newer NACS-native cars like the 2027 Bolt will need the reverse adapter if you ever want to use a J1772 unit, so you'll end up buying one of those either way. I'd also spend less time on the connector and more on whether your panel can take a 40A or 48A circuit. That's what limited me, not the plug.

Buy for the car you have. You can sort out the next one when you buy it.

If the panel can't take 40A, don't sweat it. I charge on 240v/20A with a GFCI/AFCI breaker and it's plenty for 30 miles a day. Hardwire it if you can.

One thing if you do end up looking at the Universal: don't say "Tesla" when you call for quotes. In 2018 I was quoted $1500 for a single 50A line, about 20 feet, for a Wall Connector. Two years before that, two 50A lines at about 40 feet were $800-1000. Same kind of job. Ask for a quote on the circuit and leave the charger out of it.