2 years old and can’t walk

Are there any other areas he's missing milestones? I would be concerned about the speech. Does he appear to hear well? If he's walking well inside but not outside it could just be confidence but also could be an early indication neurodiversity.

I would recommend booking into with children’s physio who can rule out a physical reason. Then I would go down the path of an occupational therapist to see if there is a sensory issue.

Thats what I would suggest

Is there a chance he is hypermobile?

Personally I would push health professionals, they're great at fobbing people off, which means children don't get the support they need in EYFS.
Just so your little one and yourself get the support you need in these early years, It's worth investigating. Mum's know their kids best, if your head is telling you that the HV might be wrong, I'd listen.

My DC has SEN and didn’t walk until he was 3. Assuming your DC is developing in all other areas, I wouldn’t be too concerned. Consultants will only class it as global development delay if there’s 2 or more areas of significant delay. That said, if there are 2 or more areas, in the most gentle way possible, please push your health professionals for investigations. Coming from someone who has been battling with the system for over 12 years now, you want to kick off the process early.

Can he say any words (or sounds that are recognisable as words)?
Is he a confident walked in the house, can he do it unaided without constantly falling, and get up on his own?

If he's not a bottom shuffler, probably reasonable to refer to physio.

Is he verbal at all yet? Can he express to you why he ‘can’t’ walk?

IIrc they suggest you take to GP if not walking by 18 months? I had similar with my now 4 year old - he wasn’t walking by 18 months, took him to GP, who suggested we monitor him for a few months and by the next time I went back he had started to walk and he wasn’t concerned. So if you are in any way concerned I would speak to your GP, if only for reassurance (I think it’s relatively common). Appreciate you have already spoken to HV, but I find GPs generally better if I have any concerns. My 4 year old has no issues with walking or running now by the way.

Maybe he doesn’t like the feeling of having shoes on or the hardness of the ground. It’s not something I would be stressing about right now. Give him time.

As the pp said, he can walk he’s just choosing not to. Which is exactly what toddlers do.

Kindly, your child can walk, they’re just choosing not to. At this age, as long as they have the skills to do it, I wouldn’t worry about it. It will come. Especially if he’s still getting the hang of it inside, or if something has put him off (has he maybe hurt himself falling over and is just a bit of a cautious child?)
My niece pretty much refused to walk anywhere for her first 3 years. She’s 7 now and still whinges about it, but is perfectly capable of running around when she feels like it. You might just have a stubborn one!
There’s also a big difference between 21/22 months and 2 years, you might find he just takes off one day. Then you’ll be wishing he didn’t…
It’s easy to say when your kids are a bit older, because I do remember how much I overthought every little thing, but try not to worry too much. If he’s still like that in a few months you might need to get him checked.

I would go see a pediatric physio to check there isn't any physical reason for it, it can't hurt really. They can also give some exercises to do at home to strengthen their legs if need be.