Hobby soldering is still putting lead into the environment, and not with any necessary justification. Lead-free solder works fine. Lead solder is a bit easier, but not enough to matter. I do know as a hobbyist myself who has lived through the transition and know all about both the old and new worlds.
The problem isn't vaporizing, or the first consumers direct exposure. The problem is taking a pound of lead and distrubuting it all over the environment in the form of spatter, shavings, assembled pcbs, connections, etc. Probably less than half of the solder winds up in a product or project, and that is just a short delay on it's trip to the envirnment when the project is discarded. 100% of it ends there, and not in a nice solid lump but practically aresolized.
It's the same as just taking that same pound of lead and directly grinding it into a fine powder and just sprinkling it everywhere, where it becomes part of the soil more or less and leeches into everything and can't be removed.
And 100,000 or a million or many millions of other people all doing the same thing, every day, for generations. Yess millions. There are 300million just in the US alone, and there are more than one person in every 300 that solders at least some times.
Lead-free solder works fine as long your soldering iron is decent. Even if the lead isn't vaporized, you'll be exposed by touch and splatter. When I learned to solder I learned on complete crap soldering irons that could barely work with leaded solder, and I developed a prejudice against lead-free. But lead-free solder has gotten better, and investing in a Weller or a Hakko will save the hobbyist so much time and frustration and ruined components that it's the way to go anyway.
If your iron can hold it's temperature worth a darn, the lead-free solder is fine. If it can't, you're going to struggle no matter what you use.
Damn right, there's absolutely no justifiable reason for using leaded solder for hobby projects today. Get a good iron, and a nice roll of SAC305 from a reputable vendor and you won't have any issues.
Does modern lead-free soldering still end up having tin whiskers? That was always the big downside as far as I was concerned. A quick internet search implies it's still a thing.
From what I understand SAC305 if not exposed to corrosive environments has a relatively low (but nonzero) risk of whisker formation. But in practice in a hobby environment it's not going to be a big issue.
Pure tin (or Sn99.3Cu0.7 alloy) is garbage, the silver helps a bunch.
For demanding applications there's apparently some even more performant alloys available today, eg. Innolot [1].
Working on vintage computers, it's unavoidable. Removing failed components like recapping usually involve desoldering machines which use heat and suction which creates spatter and waste inside of the machine and who knows maybe even toxicity that isn't part of normal soldering.
Soldering contamination mainly comes from ingestion. Touching it, having small particles of lead burn off and land on your skin, then in your mouth (or eyes, elsewhere). Even so, by washing hands and wearing light PPE it’s fine.
Because if that, many people consider the ban of industrial lead solder to be over-zealous. But that ban is in place to stop consumers being contaminated if they somehow touch the board. Also to minimise lead entering the water table once it is discarded.
AFAIK soldering is not hot enough to vaporize lead.