Though it's probably part and parcel of the budgetesque set of tablets, I'd suggest checking (with possible intent to avoid) if any candidate is an Android Go flavour.
I've had Apps that happily worked on old Android versions (5, 6?) and the newest ones (10, I think) but would not make themselves usable on intermediate (8, in the latest case) Go-subversion. Not through heavy multimedia use that the 'lite' hardware level couldn't handle, but apparently "developer not even bothered to provide support for side-versions, just clicked the main-run of versions in the installation-checker" or somesuch.
A few years back, I'd have suggested some non-tablet player, perhaps something that works
more directly with your vehicle's inbuilt cassette slot. (Wow... in searching for a link, it looks like the technology the web has very nearly forgotten! That was the
best link I could find, and still the image alone explains the actual concept if you can grasp it at all!). Though that, and indeed any other MP3-player, can also output to aux audio input like I suspect you're using (you may not even have a tape-slot, these days, and I never did patent my prior idea of a similar device that acted as a 'proxy CD'
).
Audible App, though. I presume that DRMs things rather than letting you freely put .mp3/.mpa files onto a more ipod-like device that doesn't need to power big screens and wide-spec processing well beyond mpeg audio renditioning. I've never used Audible (though I've had tape/CD/data-based audio books, transfers onto those from broadcast radio to listen to time-shifted/at later leisure, legitimately free podcast/similar downloads, possibly some 'fair use' copies of things stretched slightly over the strictest licencing interpretation but with no intent to push them onwards and into downright piracy) so I'm just assuming the obvious Protected Streaming-style of encapsulation requires you to use Audible's app (hence why you're frozen out, support having been dropped from your velnerable and otherwise trustworthy tablet).
Thus when you walk into the shop and say "I'd like the Foomaster 10 Go wifi-only tablet please!" perhaps see if there's a Demo model you can get your hands on, go to the Play Store and see if you can
find the Audible app before you even dream of passing the cash over. Or go via the web browser and see if it clearly announces "Not available for your version of Android". Easier than heading back later to get a refund once you've broken the seal on the real thing...
(Non-Android equivalent issues would similarly apply, of course. And nothing will stop a publisher from
dropping support once you think you're safe, though it might only leave you with interface Zeerust if it only stops you from taking up cosmetic updates and doesn't again freeze you out of the functionality.)
I have to be honest, this reply is probably more useful to me as a PTW (I might be looking for a new side-use non-mobile tablet, to augment my current disperate menagerie of devices), but having had some parallel issues of my own, in the past, it's also possibly an opportunity to usefully vent about past experiences.