The contribution to the viewing appointment reads... interesting. Unfortunately, such real estate agents are regularly around. Actually, the second interested party who almost wants to buy is standard. We have already experienced this with three plots of land, one of which is now listed online nearly 6 months after the call with the agent at 20k cheaper.
I would see it as an exercise for you. Don’t be too naïve, don’t believe everything the agent says immediately, and preferably research B-plans or restrictions yourself (for example, we once received a hand-drawn plan with building boundaries from an agent for a plot that in reality should not have been built on). Agents can be helpful, but often unfortunately they just want to grab their commission and do nothing for it.