It can be very common for dogs to be reactive on the lead, think about it- they cant go anywhere.
My dog is very very nervous and doesnt want to say hello to ANY dog, let alone an off lead one.
I do what i can, i advocate for her. If i see an off lead dog, i shout out shes not friendly please can you recall your dog, and i use my foot or body to block the other dog getting to her because 9/10 times said other dog has no recall.
I have been very sharp with people but thats from getting fed up of it and irresponsible dog owners letting their dogs off when they know they cant get them back.
You can get yellow nervous leads/ harnesses or things that clip onto the lead.
I walk mine on an extendable and even if we cross paths with an on lead dog, ill unclip it so she can make her own distance to walk past.
Id do some practise with 'leave it' and getting him to walk past on lead dogs without reacting using high value food treats and do some research on lead reactivity.
With off lead dogs approaching, that ones down to you to step in. I hated it and i still do, but it needs to be done.
It annoys me even more that i KNOW if she wasnt a tiny dog, i wouldnt have half the problems with people letting their dogs approach her if she was a large dog instead.
Her breed was DH's choice, and im tempted to get her a very large breed big brother 🤣