It would be acceptable if the results of the project were sufficient to make a hire/no-hire decision.
If I do one two hour project, and either get an offer letter or polite refusal in response, I'd do it in a heartbeat. But no one does that. They would be fools if they did.
An anecdote is not data, but I actually did have this happen. I did a 15 minute phone chat talking about the job and a week later had a one hour online live coding session. Two weeks later, with no more contact I had a formal job offer letter in my inbox. The offer was above market rate, and the commentary in the email from the CEO said that the offer was a negotiating floor. I actually had to ask to fly into the office s(the job was remote) to meet the team and learn some more about the company and work itself.
I ended up declining the job, and they told me that the offer would _stay open_. They even got in touch with me a year later (to the day) to see if I wanted to reconsider. This was all about a year and a half ago now.
If I do one two hour project, and either get an offer letter or polite refusal in response, I'd do it in a heartbeat. But no one does that. They would be fools if they did.