There are many ways to track corporations' spending, relationships, and lobbying efforts, but the information tends to be buried or otherwise hard to find. Typically, if information is not required to be disclosed by a regulating body like the SEC in the US, it will be even harder and sometimes impossible to find. Here are some resources and strategies to use.
Lobbying and Government Involvement
There are various ways corporations can attempt to influence government policies. Use the resources on the government tab for some ideas.
Most resources that capture business information about companies don't focus on lobbying efforts, so you're more likely to find out about a company's involvement by focusing on a specific policy or introduced bill and tracking backwards to see who is behind it. A good example of this is what the speaker Kelly Janousek talked about as her part of the "Follow the Money" program offered at ALA Annual 2021.
Keep in mind that individual companies may lobby for certain interests, but they may also be part of other organizations that do that work such as industry associations or non-profits created explicitly for that purpose, so it may be a multi-step process to track back to the company.
The company's 10-K and other filings and statements
While the amount of information included in the 10-K can vary, companies will sometimes mention key corporate partners, such as suppliers, manufacturers, and distributors as challenges or risks with those business operations can affect the company's perceived value to investors.
Companies typically disclose key executives in the proxy statement issued ahead of the annual shareholder meeting. You may also be able to find it on the company's "Investor Relations" website.
Groups, like pension and mutual funds and investment firms, that own a large amount of equities have to file the 13F form with the SEC that details their holdings. When this information is aggregated you can see who the institutional owners are for various equities like stocks and is available in many expensive financial subscription resources like Capital IQ, Bloomberg, or Refinitiv Workspace.
Deals and transactions, like mergers and acquisitions, will also result in SEC filings and are tracked by many company databases. Companies will also often release press statements when deals are announced.
Capital IQ is a subscription resource by Standard and Poors (S&P). Each company in the database has a "Relationships" tab that will provide information about key individuals at the company and the other organizations they are associated with. It primarily captures senior company executives and board members and can be spotty. You can also see people's professional activities in LinkedIn which uses self-reported data.