Good on you for asking when in doubt!
'Edible' can come in a wide range of meanings from being part of a daily diet, useful as a supplement, given carefully as a treat or better avoided altogether.
Carrot is fine as an occasional treat (mine are getting a little with their dinner every few weeks) but it is like feeding block chocolate to guinea pigs and rabbits - sugary and calorific. So nothing you want to feed regularly and rather not in processed form.
See chapter 8 in our diet guide:
Long Term Balanced General And Special Needs Guinea Pig Diets
Alfalfa in addition to normal grass hay is OK for nursing babies and at the most for up to 4 months but your babies will thrive just as well without. Alfalfa is a legume, not a grass hay and is too rich for a normal diet.
Where alfalfa hay comes into its own is as a fast protein and calcium rich feed-up for freshly rescued usually pregnant sows from neglect backgrounds - it gives them and the growing embryos what they urgently need. Normal pregnant sows don't have a malnutritional issue that is multiplied by carrying babies so alfalfa is frankly not necessary.
In nearly 20 years we haven't seen any differences between surprise babies or known pregnancies from piggies in good normal care - those on alfalfa actually were more likely to produce single whoppers that their mums rather struggled to get out but we have seen major differences in babies from newly rescued sows with a less than ideal background and not enough time to catch up. The babies were noticeably smaller all their life although healthy but as long-lived as babies born after more time in good care. Rescues see a steady rise in successful births, less fatalities as well as a rise in baby sizes over the weeks when taking in a lot of pregnant sows at all stages of pregnany - the longer in good care, the better the survival odds and baby sizes.