best shoe/insert for occasional foot pain and knee pain

Hello,
I'd like some advice on best sandal and best walking shoe for
a person who says she doesn't have much padding in her foot (58
yrs.old) and
occasionally feels a bit of arch pain.

She is on her foot a lot at home and prefers to wear sandals.

Also, she does have some knee pain, but that was due to overuse
in gardening.

Is there a good orthotic insert that is comfortable and works for
sandals?

What about shoe brands/models for this type of problem?

THANKS!