Don't worry too much about the germs as it'll be good for their immune system. I have found this spray to be good if I'm worried about germs https://www.boots.com/vital-baby-hygiene-aquaint-sanitising-water--50ml-10287480?srsltid=AfmBOooXVOe_A2yzm421JPabM_BZ3jbmVEWPQCwK8yNYfwFUmXeN9n_r
I used to take both mine on the bus regularly with a pushchair. We lived near London so transport was regular. I did get a smaller pushchair for travel. Never really thought about germs and strangers. My eldest went to nursery anyway. Plus your more likely get an old person near you. I’ve also taken the underground and train and on the whole people are usually very helpful. Even last week I was travelling with the kids 15 & 8 to see my mum and a man picked up my suitcase and carried it down the stairs.
I’ve been using the buses in Leicester since my daughter was 4 months (she’s 2 next month). It was a much bigger deal in my head than it actually turned out to be! People are very kind and lovely, you can get a Milton foam hand sanitiser if you’re really concerned about germs (but I agree some germs are good!). I’ve had it once where I misjudged getting the pushchair off and almost got it wedged between the bus and the curb - but a kind person helped me out, and that was my mistake. And I’ve also experienced the bus being too full (already got several pushchairs/wheelchair needs to get on) but that’s just part of bus travel, and has only ever happened a couple of times in nearly 2 years. And if you get on and you really don’t feel comfortable, just get off at the next stop and try again another day!
I was a bit anxious to use the bus at first but turned out to be absolutely fine. Just be prepared that if the space/s for a pram are full you might need to wait for the next one. Try going out at quiet times to start so the bus will be less full. I found people to be generally nice and helpful, including the drivers. Remember to take some toys and things for them to suck/chew on. Good luck 😊