Consultation needed! To repair or throw out?
Based on the photos you might not need any parts at all.
The chain looks pretty awful, and is likely siezed up, but a good clean is required to see if it needs replacing. I've had some ugly chains that were perfectly functional.
Brake pads is a common age item too - they get hard with age and braking performance suffers.  But pad replacements are cheap and easy.
Tyres and tubes can be affected by age, so inspect closely, and if they hold air pressure overnight you're probably good.
Grips can get tacky and feel awful, from UV.  Replacements are cheap, or you can simply wrap them in tape temporarily.
Saddles age and can attract tears, but tend to last mostly okay.  They're more expensive too.
As for the frame and mechanicals, the functionality is more important than its looks.
Folding bikes are also more useful and flexible than regular bikes.
Answer REPAIR simple at first, and see if there are any show-stoppers like frame damage.   Given you have two, its more likely to be a case of throwaway because too lazy, rather than both having the same terminal fault.