Click here to see the list of supported on-ramps. Alternatively, you can go to our bridge, expand the from options, and see what options are available.
At writing, these are the major on-ramps:
The OP Mainnet upgrade to the Bedrock release will take place on June 6, 2023 at 16:00 UTC!
There will be 2-4 hours of downtime.
See here for additional details.