Typically with OneAgents we focus on larger machines (let's call them servers for simplicity) so that we could monitor the hosted services. Servers are almost exclusively running on 64bit architecture nowadays. When it comes to desktop machines (where you will likely not deploy OneAgents, because in absence of hosted services used by other machines there is likely no extra information you will get from them), I vaguely remember the publication from a couple of years ago where it said that 95% of Windows desktops are on 64bit. Since then the proportions have likely shifter closer to 99% percent for 64bit, but it is hard to find any solid market statistics for 64 vs. 32 bitness any more (because as seen from the applications perspective it hardly matters any more).
What I am trying to say is that we do not really see a strong reason to support 32-bit solution, to be honest.
Which leads me to a question: what is the story behind this request? Why the host you want to monitor is still on 32 bits, exactly?