I carry one of those tiny wireless routers in my carry on wherever I go. If I have to buy internet on the plane or if I am in a hotel that limits the number of devices, I always connect through the router and use it as an access point for all the other devices.
The other added benefit is that all my other devices already have my AP's wifi creds and will connect to it automatically.
What do you do when wifi has a captive portal though requiring a user name and password?
I use my Samsung S10 for exactly this as it has multiple radios that allows connecting to wifi and hotspotting to share that connection with other devices. Great for Chromecasting.
I used just clone the MAC address across my iPhone and laptop and switch between them, so I guess you could use your phone to get through the captive portal and then connect with a travel router that clones the phones MAC address.
I've been thinking about doing somethign similar and am really interested in what hardware you're using for this and what your setup looks like. Do you run a VPN service directly on your router, for example?
I use the TP-Link TL-WR902AC for this, it's cheap and has a MAC cloning feature that makes it pretty easy. Unfortunately the firmware isn't updated anymore and it's missing a VPN client, but apart from that it gets the job done.
I've been intending to do the same with their Mudi (E750) and between not feeling comfortable trusting their builds and being unable to get my own working (upstream openwrt has stability issues and I guess they have some patches to make the modems work properly; still haven't been able to get a properly working image from working through their repos yet).
It's quite frustrating as it's ideal on paper but they fall on the last mile to make it practically open.
The other added benefit is that all my other devices already have my AP's wifi creds and will connect to it automatically.