Do Apple devices run using 5G or only Wi-Fi?

There are some caveats to consider, and I don't think anyone can give you a solid answer as to how well it will work.

I should also preface that my experience is based on early-generation 5G to the home, and the technology may have improved over the years.

That said, the system generally works well for moderate use cases. It can slow down, though, if you have many devices all hammering the network at the same time (the 5G radio just isn't as efficient at multiplexing a large number of simultaneous connections), so if you have a large family, with multiple Smart TVs, kids, PlayStations, and IoT accessories, you might find that performance suffers (it may still be entirely acceptable to you, which is why I say it's hard for anyone to tell you if it will work for you since everyone's case is different).

In addition, latency can be more of an issue. This may be less of a factor now, with wider adoption, but when I poked it early on, the latency was much higher than a direct wired connection. For example, on my current (fiber) connection at home I can ping my favorite sites in 5-10ms. By comparison, Verizon 5G was 50-80ms (these numbers will vary depending on on your location relative to the sites you're trying to access, so don't assume these numbers reflect your latency)

Now, latency isn't a big problem for most traffic such as downloads (in my case, it takes about 45 milliseconds longer to start the download, but once started it flows well, and 45ms is barely noticeable to the human clock), but some applications can really suffer (for example, online gaming, especially first-person-shooter games where the lag between you pulling the trigger and your gun firing is critical) (disclaimer: I spent years of my life managing an gaming network and can talk for hours about the latency aspects :) )

This may or may not be a problem for you, depending on how you're using your network. it's just something to be aware of, and another reason why there's no single, simple answer to the question of how it will work for you. :)

So, in short, the underlying back-end using 5G vs copper or fiber is largely irrelevant to the devices on your network. The costs may be lower (the provider only has to stand up one radio tower to serve a whole neighborhood, vs. running fiber down the street and across every curb), but the difference in user experience (higher latency, potential bottlenecks) may be a cause for concern.

The good thing is that it's not necessarily a binary option - depending on any service contract terms, it may be possible to get Verizon or T-Mobile to install their 5G service in parallel to your existing connection. That way you can take your time testing performance and compatibility, then cancel either the 5G Home service if it doesn't meet your needs, or your existing service if you're satisfied with the performance.

Check what these vendors are offering.

MOST internet service providers rely on a cable (either copper or fiber) to your house, connected to a router. That router acts as a wireless base station to allow local devices to connect over the air to the base station and piggy-back up the wire to the wider internet.

SOME service providers (notable Verizon and T-Mobile) offer a '5G home' service which replaces that (copper or fiber) cable with a wireless connection. However, their router still acts as a WiFi router for the home, and your devices will connect to it over WiFi.

The fact that the upstream link is 5G is completely irrelevant as far as devices in the home are concerned. They do not need 5G (or even need to be able to spell '5G') in order to work - they connect over WiFi like they normally would, and the base station takes care of uplinking over the 5G network.

THIS is what I assume you're talking about when referring to Verizon and T-Mobile's 5G service. In short, the uplink (copper, fiber, 5G) is irrelevant and transparent to devices on your network.

If I'm wrong and you're talking of a direct 5G connection for each device... well, for one I doubt that would be less expensive, based on the way these companies charge for 5G connections per device. Secondly, it wouldn't be tied to the house - the connection would work anywhere there's a 5G signal). However, none of the MacBook, AirPort Express, nor HomePod can connect to a 5G network natively (they lack the radio transmitter/receiver hardware), which is why I also doubt this is the path you're considering. The iPhone can connect to 5G, and the iPad and Watch have models that can (you'd need to check the specific model you have to see if it has Cellular support or just WiFi). But, again, I think it's irrelevant since the 5G home service creates a WiFi network in your home for all your devices to connect to.