For some additional context, the Institute of Museum and Library Services (IMLS) is the primary funding mechanism for libraries on a national level. It distributes grants to State Libraries (every state has one, though it may not be called exactly that) who then distribute that money further to individual libraries in their states. It's a federal entity that has to be reauthorized every year or that huge chunk of funding goes away, and every year of the first Trump administration the fight for reauthorization was a white-knuckle event. We got it through by the skin of our teeth each year, but it was harrowing.
Libraries are mentioned on page one of Project 2025's Mandate for Leadership (the big book of horrible policy plans). Choosing not to reauthorize the IMLS will be an easy way for the incoming administration to gut library services nationwide, especially in small communities that don't have a thriving donor base to fill those budget gaps. They'll be able to stop the "porn peddlers" and "groomers" at the cost of vital services to those communities.
One of the best tools we have to try and avoid that outcome is to prove, definitively, that libraries matter by presenting robust use statistics. Checking out books, using library spaces, attending library programs, all of that gets captured and reported to the IMLS each year. They're imperfect measures of the value the library provides to the community, but they're what we have.
At the local level it's going to be just as, if not more important to educate the community about what the library does. Your local governing authorities aren't going to be persuaded by the librarian alone, but they can be persuaded by vocal community support. That will also inoculate your community against "grassroots" attempts to shut the library down, like almost happened in Dayton, Washington in 2023.
To bring it back around to OP's original point, the imperfect nature of the stats gathered can work in libraries' favor on both fronts. It might actually be detrimental to present record-breaking circulation numbers for queer titles to the incoming administration, but the IMLS doesn't collect that level of detail. Any book you check out adds to the bottom line total that gets reported, queer or not. At the local level librarians have more control over the stories they tell with their data. If you're in a progressive community, they can be open with those more granular numbers as a way to underscore their importance as a resource to queer community. If you're in a conservative community they can lean on the bigger picture to show the impact on everyone, while knowing internally what materials are actually circulating and how best to curate the collection to serve their patrons.