I work from home as a W2 IT Security Consultant. Am I allowed to take a deduction for purchasing OSs and other software for my lab?

Yes. You could claim a deduction for software and other unreimbursed business expenses, but you would have to itemize your deductions in order to take the deduction.  Additionally, the deduction is allowed only for the amount that is more than 2% of your Adjusted Gross Income (AGI). 

It is very difficult to qualify for this deduction. That's because the expense limit is so high. In order to qualify, your job-related expenses must be more than 2% of your AGI (adjusted gross income).

Example: If your AGI is $60,000, your expenses would have to be more than $1,200 ($60,000 x 2%). Even then, you could only deduct the amount over $1,200. So, if your job-related expenses were $1,500 you could only deduct $300 ($1,500 - $1,200).

You might have other expenses you could claim, such as business use of your home.  For more information see https://www.irs.gov/publications/p529/ar02.html