There is no official list of companies in TEAs, but there are several nationally published TEA lists, so you can find the areas. Please also note the TEA rules may change soon and also the TEAs maps change annually depending on the unemployment rates.
I suggest that you go the other way around. First, find out what business you want to buy that requires an investment of at least $500,000 and then determine if the business is located in a TEA designated jurisdiction. To determine whether the business you would like to purchase is within TEA you will need to establish that the project is located within a metropolitan statistical area and also located in an area that has experienced an average unemployment rate of 150% of the national average. Unemployment rates are listed on the Bureau of Labor Statistics'' website. You also need to be cognizant of all the rules that you need to comply with when you are buying an existing business for EB-5 direct application purposes. 8 C.F.R. 204.6(h) (2) and (3) state as follows: (2) Purchase an existing business and "simultaneous or subsequent restructuring or reorganization such that a new commercial enterprise results"; or (3) Expand an existing business through the investment of the required amount, so that a substantial change in the net worth or number of employees results from the investment of capital. Substantial change means a 40 percent increase either in the net worth or in the number of employees so that the new net worth or the number of employees amounts to at least 140 percent of the pre-expansion net worth or number of employees. The establishment of a new commercial enterprise in this manner does not exempt the petitioner from the requirements of 8 CFR 204.6(j) (2) and (3) relating to the required amount of capital investment and the creation of full-time employment for ten qualifying employees. In the case of capital investment in a troubled business, employment creation may meet the criteria set forth in 8 CFR 204.6(j)(4)(ii).
For EB-5 processing, the usual process is the investor locates the business that he potentially wants to invest in, and then determines if the business is in the TEA. Or, the other option is to find regional centers with projects that have already been designated to be located in TEAs and invest in one of those.
TEA determinations are mostly on an address-by-address basis. Some areas of each state may be pre-designated, but mostly the specific address is sent to a state agency that makes a determination. As for a project database, there are a few websites that try to list as many as possible, but since there is no requirement for a project to be pre-approved by USCIS, finding projects is often done with your professional team members (either to find options or turn a business into an EB-5-compliant project).