You could theoretically also download every single patent that has been filed in the last 25 years and then go back and patent them earlier.
I'm pretty sure being able to release lithium ion batteries in 2001 would make a dramatic change in the world and make you a billionaire in and of itself.
Perovskite solar cells would be a great follow-up to that, and you could revolutionize computing by knowing how to make raspberry pi's.
Obviously as you work your way up the tech tree you need more and more money and more and more time but once you have the blueprints for the technology everything after that is money and manpower.
For instance, risc v is Open source hardware. You could quite easily develop the lithography processes needed to create the CPUs and be a thousand steps ahead of Intel in developing cutting edge top of the line computers. Combine that with releasing a modern Linux kernel with an OS to match for free along with the hardware purchase and you could completely destroy Microsoft, Intel, AMD, Apple and Google in a fell swoop.
In 1999 I think the fastest processors were at what 300 MHz, maybe 600 something like that, Risc V processors are commonly available today running at 1.85 GHz along with graphics abilities that would blow away anything that existed in 1999.
You would also need to redevelop flash storage and RAM to match, and it would probably be a good idea to roll out Wi-Fi as well, but if you had a billion dollars by the year 2000 and all of the equipment you could easily see these things being released by 2005 and not be beholden to any shareholders.