My friend does this when they go to the USA
A 256Gb microSD hiddden in luggage with a fully updated MX-Linux installed.
Create a snapshot of the updated system on a MX-Linux live CD including all the programs you would normally use, VPN etc, save it to a usb drive and write that to your microsd card.
sudo dd if=snapshot.iso of=/dev/mmcblk0 bs=1M status=progress
meanwhile, install a new HDD drive on an old laptop. wipe it and install any new linux distro. you wont be using this at all
at your destination, input your microsd card into laptop, change boot order and boot into your new microsd card,
The microsd card leaves no traces, it runs in memory.
A freshly installed Lineage on an older phone.
you wont have to unlock anything, you will have nothing on your laptop or phone
border force can access everything. there is nothing to see!
get a trusted friend to send you any important files via signal or any other encrypted messaging or email service
At your destination, login into your emails and messaging services etc
Everyone can come up with technical ways to backup and wipe. The most interesting question is how you answer questions like "it's clearly wiped/burner, do you have backup accounts, sir, and how you're gonna restore and can we have these passwords?". Because everyone is a hacker hero until faced with the option to lie to border control and get called out either way.
Your worst enemy here is a thought that they are stupid and that you can confidently lie in a tight room, surrounded by police officers. Neither is true.
I would advice caution with that approach. Not only could Linux by itself be "suspicious", a clean OS without any data surely is. Once they have a justification for a deeper search they will find out about the live OS and you will be treated like a terrorist.
A better approach would be to backup your OS and make it available online over SSH/VPN for example. Then install windows or any other default OS on all devices with some amount of believable but not too personal data. Once you are over the boarder wipe all devices and download your real OS and data over the internet to your devices.
Genuine use for an LLM right there
I might have to look into a live MX Linux. I've been trying to make an iso of my current Kali install for VMs and it just won't work - won't even create the image successfully. And of course Kali doesnt have an accessible image for Kali everything either. Really frustrating.