According to the National Center for Home Food Preservation, you can use other jars for canning. I know that's not what you're doing, but canning is pretty rough on jars and the pressure used in an instant pot (approx 11 psi) is lower than the pressure used in pressure canners (approx. 15 psi), so I think it's a good basis. However, there's a greater chance of breakage because the glass quality may or may not be lower than a traditional mason jar.
See this link for more info:
http://nchfp.uga.edu/how/general/recomm_jars_lids.html
If you want to, go ahead and try it, but if the glass shatters, I would replace the silicone seal on your instant pot and make sure you clean the lid thoroughly. I'd also do a water test just to be sure. (So you can decide if the cost of just purchasing a mason jar or two is worth the risk of losing a sealing ring--the same quality as ones used for canning can be purchased individually in the craft section of most stores).