There is a pretty good multi-billion-dollar program for biodefense that the Biden administration is pushing for.  You could try to support those goals either by contributing to Guarding Against Pandemics, who are lobbying to make sure that said plan actually happens.  Or you could try to invest in some more speculative pandemic-prevention technology that isn't covered by the government spending plan; this 80K interview talks about the potential to create broad-spectrum tests for many different infectious diseases and doing metagenomic sequencing to identify new viruses.

Here are some posts describing key EA priorities in biosecurity.  Not all of these are relevant to immediate covid relief (creating sealed underground bunkers to guard against X-risk is not going to help anyone right now), but some of them are (like investigating UV sterilization technology and designing better forms of PPE):

• A list of Concrete Biosecurity Projects from Andrew Snyder-Beattie, who is in charge of biosecurity at OpenPhil.  It goes into detail on:
  • Creating a pandemic early-warning center specifically focused on detecting new, unknown pathogens.
  • Designing improved PPE and then convincing the government/military to buy a bunch of them.
  • Research into broad-spectrum medical countermeasures (like the pan-coronavirus vaccines that some labs are currently working on) and rapid-response platforms.
  • Strengthening the Biological Weapons Convention in creative ways, like with a whistleblowing prize. (There's kind of a running EA joke about the pathetically small budget of the Biological Weapons Convention part of the U.N.; they only have something like four employees.)
  • Fundamental science research into improved sterilization technologies along the lines of UV light, antiseptic materials, etc.
  • Specially designed underground bunkers.
• Here is a Forum article about biosecurity projects for engineers and materials scientists.  Will Bradshaw is interested in chatting to anyone this stuff in more depth and I'm sure he'd love to talk with you if you wanted.
• Here are a bunch of brainstormed bullet points about small projects that might be helpful, including lots of smaller stuff on the level of research that a single graduate student or small team could be funded to produce.
• Of course you could peruse the past grants of OpenPhil's biosecurity program.

Some other things that come to mind:

• Maybe some kind of advocacy effort to implement stronger bans on gain-of-function research, or even just collecting and presenting data about BSL 3 & 4 labs, where they are, their history of leaks/accidents, etc, along the lines of how Covid Tracking Project, OurWorldInData, and other organizations will compile datasets as a form of journalism and advocacy.
• Here is a List of Possible FDA Reforms that might be worth trying to push for, either in the USA or among the health regulators of other nations which are probably in similar situations.  1DaySooner would probably be a great place to start.

I'm not sure if these ideas satisfy the "non-obvious to fund" specification in your question, but hopefully something here has been helpful!   Sorry that these suggestions have been so heavy on advocacy rather than science; I am not a biologist or anything so I don't have a good picture of that space.

Sounds great! Could toss some more money to 1Day Sooner to work more on advocacy for human challenge trials?