Damn that’s convenient!
Yes, the simplest adapter style is a chunky wall wart, usually cheapest. Otherwise inline modules are common. For either, you just plug them in between the plug and its outlet and press the “reset” button. 15-amp 125v example from a common US supermarket ($14).
And if by extender you mean the multi-outlet strip extenders: yes, the adapter+extender would isolate the fault to just that strip. If ground fault occurs, everything on that strip turns off. You can also find power strips with built-in GFCI.
The only additional consideration re: which GFCI adapters you will need are
- Voltage and amperage rating: you can just copy the rating of the outlet’s breaker

…or, if it’s just handling one appliance, take a picture of the power specification, usually a sticker on the back of the appliance, which should give you minimum amperage rating of GFCI

- Socket type: if you’re in the US, likely all type B or maybe one or two type I (large 220V appliances) from this chart:

Edit: pictures