>Maintenance may involve Huawei technicians, etc.
Who are not Chinese nationals. Working for foreign company subsidiary does not change your national allegiance.
Vendor lock-in is not the issue. If we get into conflict with China and it takes, say, 6 months to swap out all the now-compromised Huawei hardware (which is obviously insanely optimistic), that’s a problem. Wars have been won and lost with much less than 6 months of technological/infrastructural head start.
Do you think a nation-state like China will have great difficulty compromising non-Huawei hardware? This seems overblown because Huawei components will be a small fraction of the attack surface in very connected environment. The best defence would be vendor-agnostic, which might be what the UK government is planning on.
Also, it would afford them the additional political benefit of deniability in their attack.
There technically isn't, but 3GPP standardized interfaces leave enough room for there to be a smoother deployment and operational efficiencies gained from a single vendor deploying RAN and Core together. Few suppliers can do this -- Huawei is one of them.
>>Who are not Chinese nationals. Working for foreign company subsidiary does not change your national allegiance.
Maybe this is region specific, but I believe most (all?) initial Huawei deployments are performed by Chinese nationals working directly for Huawei. To your point, maintenance (i.e. post-deployment, live production) can be a mix of foreign company employees and Chinese nationals.
Regardless of whether using Huawei tech makes you vulnerable to spying or not, it still means you are bound to Huawei products and infrastructure through vendor lock in. Maintenance may involve Huawei technicians, etc.
We should be actively trying to separate from China, and it's unfortunate many seem eager to do the opposite.