New gran here so excited but a bit worried about keeping up!

Glad you are so happy with your new g.son. He is not smiling at two weeks old, just looks like maybe when he has wind.
Surely, it his parents who need to know about baby care. If he i being breastfed, then he is receiving lots of protection from that.
Most small children are walking germ factories, and it is the adult who is likely to catch things from them - any new primary school teacher knows how often they will be ill during that first year.
\stop worrying and just enjoy - you have many years of it to come. Be there now for new parents, not intrusive but to give them help in whichever way is best.
Make sure you keep up with any vaccinations for flu and covid and do not forget your shingles vaccination.

I would save your energy until he's a toddler- until then it's all aabout cuddles, nursery rhymes, cleaning up sick and snotty noses.
You don't need a certificate of health to be a gran- just enjoy and keep quiet about things you see and hear that you might not agree with.
I would say a shut mouth is far more necessary that a health check!
Grandma of more than 12 years...

I was apprehensive when DIL went back to work (part-time) and other Granny and I shared baby-minding duties.
However, it all came back again and it was a very enjoyable time. I was older than you, too.

Be guided by the parents, stick to their rules. Although I must say DS and DIL didn't give me any really.

I agree with butterandjam, what I did was voluntary work in a local crèche to get right back into the rhythm, it did mean getting an enhanced dbs check. I would say it was invaluable for getting back into the rhythm.

By age 60, you know well enough how to keep as healthy and strong as possible; fresh air, sensible diet, excercise, sleep well. . Don't smoke , limit alcohol intake. Now you've got a great incentive; to be a fit active granny.

In a few years time your grandson will probably like to be taken for walks, a swim, skating, a bike ride. So if you can't swim skate or ride a bike yet....you've still got time to learn :-)

Well that’s probably wind, they don’t smile at 2 weeks🤗

Please don’t worry it will all fall into place and then you ll remember all the things you did with your babies (a few things will have changed so go by your daughter or daughter in laws ideas and ‘rules’)
You can’t keep them snifflefree once they are out and about and meeting people but hopefully that will be a bit later on and by the time you are needing energetic play it ll be springtime plus he / she won’t be doing much apart from eating and sleeping for the first few weeks/months then just do whatever the mum wants you to do they may not be much interaction while the baby is so young unless you are to be a designated carer when she goes back to work
Go with the flow ( do as you’re told) don’t worry too much and enjoy this new little precious bundle

It's very early days yet. It's up to mum to look after the baby. Nobody can keep themselves in perfect health. You may catch coughs and colds but baby's immune system needs to be challenged to develop. Can't be wrapped in cotton wool. No reason why you should tire yourself out. Give it all time.