Thin clients are just display devices, completely incapable of anything without a server.
They could definitely do some local computing. Most notably to me is that by the mid 90s you could stick your credit card in and it would negotiate with the chip in the card so you could buy something securely.
(Apologies to American readers who didn't get chips in their cards for another couple of decades)
This isn't necessarily evidence of local computation though – the EMV protocol is fairly lightweight (even for 90s standards), and I could imagine a remote EMV terminal implementation, with the handful of ISO 7816 APDU exchanges required for a minimal payment being sent over the network.
That's how e.g. the Nintendo 3DS can support Suica payments, which is another amazing (and to me unexpected) application of a normally merchant/terminal-side payments technology in consumer hardware.
I’m 2018 I went to visit my family in Australia. Only one of my US cards had a chip but I called and got a different card to send me a chip version so I’d have two.
Got home, tried to buy a coffee and the bloke behind the counter called out to a colleague “hey, do we still have a way to pay with a chip?”
(Of course most places did, but it was on its way out)
I wonder how well (or if) that works with European-issued cards – some issuers require these to be inserted and a PIN be entered every few payments to reset the internal risk counters.
Yup, sounds like what happens when you power on a minitel. They are essentially thin clients as far as I know. Most setups I've seen had these plugged into the same outlet as a nearby phone. You would power on the minitel, pick up the phone and dial the phone number of a remote server ("3615" was the common one). Text would start appearing on the minitel with a landing page that acted as a service index and where you would be able to type in the name of the service you wanted to access, for instance SNCF to book train tickets.
For instance this is a low quality video of someone using the 3611 phonebook in 2009: https://www.youtube.com/watch?v=fS3DazMR3QY
There seems to be a few other phone numbers that you can still dial, hosted by individuals: https://www.youtube.com/watch?v=F2mgDSBWOxI