In that time slot over the last 5 years (data below), the games break down as such:

3 games of PAC12 vs other P5 (average viewership is 1.74M)
24 games of PAC12 vs PAC12 (average viewership is 1.56M)
2 games of PAC12 vs G5 teams (average viewership is 1.46M)
4 games of PAC12 vs BYU (average viewership is 1.30M)
2 games of G5 vs G5 (average viewership is 1.13M)
3 games of BYU vs G5 (average viewership is 766k)

As an aside, I'd lean towards ignoring those BYU vs G5 games since the G5s BYU played (W Kentucky, Tx St, Troy) were SO bad.

Worth noting however that the two most recent BYU games drew almost nearly as much as an average PAC12 in-conference game would get in those same time slots.

ESPN 10:xx EST Saturday Night College Football Game Viewers

1. 2018 Michigan St / ASU (10:45) 2.297M
   
2. 2017 Washington / Arizona St (10:45) 2.277M
   
3. 2017 Arizona / USC (10:45) 1.939M
   
4. 2019 Wash St /Oregon (10:30) 1.90M
   
5. 2019 Washington / Stanford (10:30) 1.88M
   
6. 2019 Stanford / USC (10:30) 1.86M
   
7. 2018 ASU / Washington (10:30) 1.834
   
8. 2019 Texas Tech / Arizona (10:30) 1.73M
   
9. 2017 UCLA / Stanford (10:30) 1.677M
   
10. 2019 USC / Fresno St (11:00) 1.65M
    
11. 2017 Cal / Washington (10:45) 1.634M
    
12. 2019 UCLA / Arizona (10:30) 1.63M
    
13. 2019 Arizona / Oregon (10:30) 1.61M
    
14. 2018 Utah / Washington (10:30) 1.589M
    
15. 2018 Cal / USC (10:30) 1.587M
    
16. 2018 Arizona / Wash St (10:30) 1.568M
    
17. 2017 Utah / Washington (10:30) 1.537M 
    
18. 2021 Utah / BYU (10:15) 1.503M
    
19. 2021 ASU / BYU (10:15) 1.498M
    
20. 2018 Cal / Wash St (10:45) 1.495M
    
21. 2019 ASU / Arizona (10:00) 1.44M
    
22. 2018 Utah / Stanford (10:30) 1.415M
    
23. 2017 Colorado / Wash St (10:45) 1.392M
    
24. 2019 UCLA / Wash St (10:30) 1.39M
    
25. 2017 USC / ASU (10:45) 1.381M 
    
26. 2020 USC / Utah (10:30) 1.33M
    
27. 2018 BYU / Arizona (10:45) 1.288M
    
28. 2017 Boise St / Washington St (10:30) 1.265M
    
29. 2017 Cal / Mississippi St (10:30) 1.195M
    
30. 2018 Oregon / Arizona (10:30) 1.186M
    
31. 2019 Washington / Colorado (10:00) 1.18M
    
32. 2019 Wyoming / Boise St (10:15) 1.18M
    
33. 2018 Boise St / Utah St (10:45) 1.078M
    
34. 2021 Arizona / BYU (10:30) 0.933M
    
35. 2020 Troy / BYU (10:15) 0.795M
    
36. 2020 W Kentucky / BYU (10:15) 0.788M
    
37. 2020 Tx St / BYU (10:15) 0.716M
    
38. 2020 Utah / Oregon St  (10:30) 0.702M