As the OP mentioned, I’m not going to get into the rechargeable vs disposable battery HAs debate because we’ve all really beaten that horse to death. My next HAs are going to be rechargeable, in fact.
But I’m going to add to what @cvkemp and @SpudGunner said about needing to bring backups on a trip if the HAs are that critical for you. It’s not just backup for the Smart Charger, but it’s also backup for the HAs, because it easily could have been the HAs that died on you and not the Smart Charger. Neither of those things take up much room to pack a backup for anyway.
While I really don’t have any suggestion about trying to get the Smart Charger to work other than what’s already been mentioned (like try to clean out the USB port or giving the charger a mild whack in case of loose connections or find a local Oticon HCP), one thing you can try to do is maybe buy a pair of Apple Airpods Pro earbuds (preferably the gen 2) because they should be readily available for sale at a local electronic store. I hear that the Airpods Pro can allow you to enter your audiogram (or use the Mimi app to test your hearing live) then compensate to your hearing loss up to a degree in its setup. Then you can either wear it using Live Listen which will then use the iPhone mic to pick up sounds, or I also hear there’s a transparency mode so that you can use its own dual beam forming mics to pick up the surrounding sounds. I don’t own the Airpods Pro (2) so I can’t really help you with any details, but that’s what I heard on the forum.
They say that for folks with mild to moderate hearing loss, the amplification compensation from it may be sufficient to be adequate for your hearing need, although it’s still far from replacing a real HA. If you find this solution helpful, maybe the Airpods Pro 2 can serve as your last resort backup for hearing next time you travel as well. It can double for listening to streaming music as the bass delivered from it should be superior to that of a pair of HAs. In fact, I hear that Costco is having a Black Friday sale on it right now for $199 from $239, if you can find a local Costco near you. If you decide later that it’s not helpful enough for you in the long run, you can always return it to your local Costco when you get home.