Both of these sentences feel wrong to me:
if I am alone, I will go today
if I would be alone, I will go today
By looking up some rules, it seems that using
would in the protasis is a common mistake, even if there are a few exceptions of the form
if I would [verb], then I would [verb] (but given that the protasis is "more in the past" than the main clause, shouldn't it be
if I would [verb], then I will [verb]?).
On the other hand, the common example of conditionals with the verb "to be" are things like "if I am lucky...", "if I am able...", "if god is...". In all of those cases it makes sense to be uncertain: we don't know yet if we are lucky in a certain circumstance, for example.
But it wouldn't make sense to write "if I am alone" right now: I should know already! Either I am alone or I'm not... In which case I should just drop the conditional.
Context: a friend that is learning English wrote
if I be alone, I will go today
"If I would be alone, I will go today" (if there's a chance that you might still go, if your friend might not be with you for the whole day) "If I were alone, I would've gone today" (for an unreal past situation: you know that you were not alone, and the decision has already been taken)
I can sidestep the issue with something like
If I end up being alone, I will go today, but I'm concerned that my previous suggestion to them might've been ungrammatical.