Reading your experience, I would say that the company appears to have handled the situation very poorly. There's a few different elements at play here though.

Probation period. If a company doesn't think you're up to scratch by the end of the probation period, they let you go. I've never had the experience, but my father has and my understanding is they pretty much can just say "sorry, we don't think you're up to our standard" and that's that (note: I'm in Australia).

Which gets to the first bit of poor management, because they've sat you down to have a serious meeting and pressed you on why you haven't performed (from their perspective). Highlighting lack of experience and training is a good point, and here in Australia that would absolutely be sufficient reason. I'm not a lawyer, but if you went to an Industrial Relations court over unfair dismissal and argued your case based on that, I suspect it would find in your favour.

On the other hand however, you should have stated the obvious after that. Remember that for most abled-bodied people, disability is taboo. If they bring it up, they feel they must be committing discrimination etc. I don't know your condition or what you were thinking at the time, but I suspect it was something like "if I admit my vision impairment could be problematic, they'll absolutely have grounds to let me go because visually inspecting properties is a core duty". The thing is, if that was up front, it makes it even worse that you weren't provided with sufficient training. With sufficient training you would have known "ok, this is what is required, these are the things I need to identify, these are the challenges I have in doing so because of my sight". You can then work with your employer to develop strategies to complete your duties to their satisfaction.

I've said on this sub previously that I usually don't raise my sight with potential employers. Your experience is a very good example of when it is important to raise it with your potential employer/employer, and be properly across the tasks you need to complete - I'm not saying you didn't do your best in this regard, you don't mention this aspect, I just mean as general advice for blind/vision impaired people.

Finally, I'd advise against seeing a conspiracy in their actions. Maybe it is the case, but no body likes a man (or woman) with a chip on their shoulder. Focus on the aspect of the company's poor management of you as an employee. Learn from that experience and identify strategies for next time (push for more training etc). I'm not sure what the situation in the UK is, and you might have recourse given the way they handled your situation as I mentioned above. I probably wouldn't bother though.

The problem with any industrial relations dispute is that once it escalates to that level, you aren't going to want to work for the company unless those in management change, and they aren't going to want you to work for them either. The best case scenario is you get some money out of them. But you weren't with them for long, so I suspect you wouldn't have claim to much even if you were successful.

So it is best to dust yourself off and move on.

Addendum: I wrote all the above and then remembered I actually have a story about where my sight did impact my duties at work (actually, I've two, but this one is relevant. The other is a more amusing one where I almost distributed classified information to members of the public). In university I worked retail at a consumer electronics store. We closed up one Thursday night, but I forgot to bring the bin of $2 Vodafone sim cards inside - I didn't even notice they were out there. Subsequently they were all stolen that night.

The area manager got involved in the incident (as he should), and I had a meeting with him and my manager from the night. It was my manager who actually brought my sight up and said "You didn't even see them because of your sight did you, Terry_Pie?". I responded in the affirmative and said that I didn't even notice them nor did I realize they weren't inside. The area manger nodded and told us both to be more careful next time and the issue was considered closed.

I was just a casual, and any other staff member would have had a written warning at the least, if not having their shifts cut or being dismissed. But by saying "I didn't see them" (which wasn't untrue), taking any such action would have been discrimation and I would be protected by law.

If you had had the experience you did in Australia, if you said "I'm vision impaired, I didn't see those issues" and they haven't made reasonable efforts to make your job accessible (i.e. appropriate for you, as mentioned above) and they dismiss you: that's discrimination, and I'd be even more confident an industrial relations court would find in your favour.

US?

No matter where you’re located, sorry for your troubles. Depending on your location you may have some recourse, disability protections may very location to location but I would be surprised if there wasn’t something.