Things are as rare as you want them to be (yeah, I know, not an answer, but it is... It's just not an easy answer). But your commentary is good.
Oh, sure there are satellite phones (and maybe Starlink?) in Afghanistan or the Central African Republic, even though locals could probably barely sustain TL5 manufacturing, but the amount of trade across interstellar distances might not make the equivalent of the Afghani solar farm practical to support (Still, there are probably Chinese solar panels brought over the passes on pack mules).
But the common trade goods are probably the things that are so widespread that they really are 'common'. At least in principle, at a starport. But that doesn't mean you'll see them outside the port and immediate vicinity. It could be that some local is reexporting a batch of TL10 common electronics that couldn't find buyers because the local tech infrastructure couldn't support the power needed to operate the KitchoMatic 5000.
One thing I like about Star Wars is the design aesthetic: out on the Rim, it's not all new and shiny. You will likely get your droids used from a Jawa and have them repaired by some kid in a back-alley shop. That mix of local tech (adobe buildings and tents?) sprinkled with not-so-gentle-used high tech is what I'd expect to see. Might be that you can find a laser rifle in some back alley, but nobody has a working power pack for it...
Also... don't stick your hand in a K'kree's mouth. Just because they won't eat meat doesn't mean they won't bite it off and spit it out. Or so that Hiver over there just told me, so it must be true.
That fits my universe view as well. If course since the TL of a planet is not generated wholly in isolation from other factors the likelihood of having a very low TL planet with a highly developed Star Port is nil anyway. Class A port means TL minimum of 7 assuming no mad governments.
A planet with odd atmosphere and hydrography will be getting a significant boost as well as small planets and even low population planets so generally TL10 being available (though not necessarily common) seems to be a reasonable assumption across the board. You may have to go all the way to Toche station to pick up power converters, but they are not going to be sacred artifacts.
"Normal" planets that are in the 6-8 range in their characteristics can get by with low tech. Again that doesn't mean it is not available, it just means nobody is that bothered living their lives by it.
Motmos for example is TL5 and has a Class B star port, but it is a garden world. It is probably full of hipsters who prefer a library full of books to a Kindle. That doesn't mean they won't use fusion power (as it is the greenest energy source) but they may not have overhead power lines everywhere for aesthetic reasons, limiting the power to an in home system (possibly hidden away). Grav vehicles are so noisy and you can't appreciate the scenery moving so fast, bicycles and airships are far more serene and cool.
Inchin on the other hand is TL10, but the impression I get is that most of that tech will be concentrated with the dictator and little will trickle down to the plebs. My trade experiment there was typified by a depressing lack of market opportunities. Those living out in the desert are likely to be living pretty meagre lives and the advanced technology they do have is likely to be robust survival gear (like the Fremen in Dune or maybe the Skywalkers).
Pavabid is TL6 but it is specifically isolationist and we know for example that Grav technology "doesn't exist" because the theocracy darned well says so and that floating palace is because of Gohdd! They probably don't have much in the way of comms infrastructure either, but that just stops heresy from spreading so that is entirely orthodox. Pavabid has an entirely adequate star port, it's just the locals can't visit it and so advanced technology will only exist where the Theocracy allow it (so the majority will be with the Son of the Star). We also know it is a routine task to land a ship in the hinterland without anyone noticing as Pavidians are not permitted to leave the planet, yet there is a sizeable Pavidian diaspora.
These largely random TLs have been turned into story drivers rather than equipment limitations. Like Star Wars even a systems TL will flex depending on the application (Sand Trooper rides on Dewbacks rather than AT-STs but they still have blasters). Logistic support is not just a matter of TL, but TL might be heavily dependent on Logistics support.