@loop2u my youngest dd has had Guinea pigs since she was about 5 and is now 11. She wasn't able to help much at 5 but now basically does all the care. She cleans them out daily and cuddles them and is very confident and careful handling them.
I do the nail clipping and bits that are more delicate.
They aren't that hard to look after but that depends on where you keep them and how much attention you want to give them.
If you want them to be happy being handled they need practice with that. Although a couple of our rescues aren't happy to be handled, they don't tend to bite. I think in all the years only one of us was bitten and that's when dd was holding her fingers out to one and had cucumber juice on her. It was a hungry bite rather than an angry bite.
We have ours inside and I think that's played a huge part in dd spending so much time with them as they are easily accessible. I have a friend with outdoor pigs and her kids have to make more effort to see them, and it's especially harder in winter or rainy days as they need to go to the end of the garden.
In summer they can be outside enjoying the grass though, even if they are indoor pets.
As ours are inside dd likes to sweep their fleeces twice a day (takes less than a minute). But they don't need doing as often as that. Maybe every other day at the least though as they end up treading in it and making more mess/getting smelly.
Their fleeces I wash around once a fortnight.
I find nail clipping can be a faff with some of the less cooperative ones. But it's easily doable (especially if you get ones with white claws). And if they are tricky you can take them to the vets and have the nurse clip them for about £15 every 8 weeks ish.
I really think they are underrated as pets.