Hello Ghaiweceeth61
At SBB exchange offices, you can reserve currencies, including 1 USD banknotes, either at a salespoint or have them sent directly to your home. While specific details about reserving a large quantity like 2000 pieces of 1 USD banknotes are not explicitly provided
For detailed information on the availability and the process, you may need to visit sbb.ch/en/change.
I wish you an excellent Sunday.
Greetings
RahelW