One "work-around" is tapping into your friends and family.
I know I have a box of old smartphones. Most folks probably do. I've been in the Apple eco-system for well over a decade, so have the normal pacing of models that lots of folks have - every other or every third iteration.
So, say your sibling or child or tech-savvy friend is on the latest Samsung or Apple phone, odds are that they took their older (but very viable) cell, migrated their stuff, and then tossed it in a drawer or box somewhere as a "back-up" in case they lost their new phone. That never happens :D so all of a sudden, they have an iPhone 6, 8, and 11 somewhere gathering dust, and if asked, they would surely say, "It's yours!". A minute to wipe it clean (of dust and old user data), and you're good to go! Add a cheap SIM or an eSIM and you can be all set for museums. If you don't want to do a SIM, you can still just wait until getting to the museum, join their free wifi, and scan their QR code, and boom! On your way. Also, if you know the museums, you can proactively download their app or other stuff while at home over your own wifi.
Keep in mind, an Apple iPad, a Samsung tablet, and maybe a Kindle Fire (are those still made?) all will function in the museum exactly as a smartphone would - ie connect to free wifi, stream the audio, and allow other "smart" features. No "phone" required.
A slightly different work-around, if you are travelling with someone who DOES have a smart phone and will be using the museum guides with you is simply to share the audio - ie you get the left ear bud, and they get the right ear one. It works best with somethin like an airpod, but can work with wired (don't recommend except in a pinch).