What kinds of audio recorders are a safe bet for day-to-day interviews?
If you're concerned that your equipment might be seized, then an iPod touch might be a good choice, since it's small, has disk encryption, and doesn't have a SIM.
You can also use a DSLR to record audio. The memory chips are small, and therefore easily concealable, but if a chip is seized, it can be read, since it's not encrypted.
Which small and portable new-model laptops, when properly configured, can hold their own at border crossings?
Well... that really depends.
Microsoft escrows the disk encryption keys for laptops running Windows 10 "home edition," so customs could seize your laptop and request the key from Microsoft. Depending on which government they represent, that may go well for them, or not.
Microsoft claims not to escrow disk encryption keys for Windows 10 "professional." This is certainly better, but tackling your question from a "product," device, or software perspective misses a fundamental reality.
At a border crossing, customs will either:
-Let you pass (yay)
-Stop you, seize your device and read its contents (no disk encryption)
-Stop you, seize your device, send it to the lab and decrypt it (woops, Microsoft betrayed you)
-Stop you, seize your device, send it to the lab and fail to decrypt (you may never see your laptop again, and if you do, you don't want to use it)
None of these are good. Refusing to decrypt a laptop is not a situation you want to find yourself in; you have already lost. Customs can detain you for hours, you lose your device, and you probably get added to a few lists for your trouble. That's just customs. If you refuse to decrypt in the course of a criminal investigation, you can be jailed for contempt of court, potentially indefinitely or until the judge concedes that there is no use jailing you any longer, since you obviously have no intention of complying. In the U.S., this can be 18 months. No one wants that.
A better question would be: which people, when properly motivated, can hold their own at border crossings?
Snark aside, it's much easier to transit customs with a newly bought laptop, or no devices at all. Have a friendly browser history full of innocuous pocket litter and a bland set of documents in your home directory as well.
What brands or products should be avoided due to supply chain or other issues?
If you buy a Lenovo "consumer" laptop, as opposed to one of their "professional" laptops (the Thinkpad series), then do not trust the factory OS install. Lenovo has a history of installing malicious software, including a root certificate used to MITM the end user's web traffic, at one point.