It's good to see your callers can now use your Obi Auto Attendant.
If most calls from the aa use SP2 (Rynga), then you can arrange for callers to simply dial the number after selecting Option 2, so they will not have to use the **2 code. To do this click on your Obi number in Obi Dashboard, then follow menu choices to Obi Expert Menu. Then do this to make this change:
Voice Service > Auto Attendant > PrimaryLine > SP2 Service.
To make this change you have to first uncheck both boxes to the right of the Value field, leave them unchecked, make the change to SP2 Service, click on submit at the bottom of the page, wait two minutes for the Obi to reboot.
If you make most of your calls from the phone attached to the Obi using SP2 (Rynga) then change as follows:
Physical Interfaces > Phone > Phone Port > PrimaryLine > SP2 Service.
Whichever service is set to PrimaryLine does not require the ** codes.
The other changes you mention could get quite complex involving "single-stage dialling". You need to very comfortable with making complex changes to DigitMaps etc. Have a search on this forum and you will see what I mean!
Putting Rynga onto a voice gateway is probably possible, if Rynga allow making calls without registration. This would free up SP2 for another provider. However, you cannot use a voice gateway as a PrimaryLine, so callers would be back to using a ** code.