I received a new Insignia Voice Speaker for work. It has a 2-prong cord, but all of my office outlets are 3-prong. I'm not finding a converter for this arrangement. Is it safe to plug the cord in as is?
As already pointed out, yes you can. But maybe understanding the why will help:
From this article, "https://electronics.howstuffworks.com/everyday-tech/question110.htm"
"The idea behind grounding is to protect the people who use metal-encased appliances from electric shock. The casing is connected directly to the ground prong."
So, chances are the device you are using would not electrocute you if a wire became loose inside and touched the casing. That is why there is not a need for the ground prong.
That 2-prong plug is a NEMA 1-15 type.
The universal-in-US NEMA 5-15 socket (Mr. Horrified) is specifically designed to accept both NEMA 5-15 and 1-15 plugs.
You will also run into NEMA 5-20 sockets (Mr. Winky). These are specifically designed to accept NEMA 1-15, 5-15 and 5-20 plugs.
The first number (1 or 5) is the NEMA series number. The second number (15 or 20) is the ampacity. North American utility receptacles are all 15A or 20A rated/breakered.
If you really, really, really want 240V in that same form factor, look at NEMA 6. It's rarely used in the US, but it's in the catalog and most hardware stores stock all the parts.