Kyiv, Lviv, Odesa, etc. are relatively safe. There's no chance of those cities getting actually invaded anytime soon, if ever. As for air strikes, just walking around it shows that the actual chance of getting hit is relatively low: the vast majority of buildings don't have any damage from the war. Some do of course. But it's well under 1% in almost three years of full scale invasion, and even if you did happen to be in one of those buildings, more likely than not you'd be fine if you're sensible during air raids. Main thing is get under cover if you actually hear things getting shot down. Though in my experience Ukrainians in those cities almost completely ignore air raids. Eg I was having dinner once in an outdoor restaurant, and something loudly exploded relatively closely to us (~2-3kms?) a few minutes after an air raid started. Literally no-one did anything other than flinching from the loud bang.

Other cities closer to the front line are much more dangerous. Eg in the Kharkiv area, Russian forces are close enough that they're able to hunt down civilians with drones and drop grenades on them. They're straight up bragging about it publicly, and publishing the videos, apparently calling it the "human safari". And from what I hear, a lot more buildings in Kharkiv have been hit; being closer, you get a lot less notice to take cover.

I wouldn't hesitate to visit Kyiv. I'd want an actual reason to visit Kharkiv.