Amel Tuka has run 100m in 10.93 (in +3.0 wind). This was in 2018 and he had some sub 1.46 races in the 800m that season.
Way back Jonathan Johnson ran 100m in 11.03 and he was a quite speedy 800m guy.
Slimane Moula has run 200m in 21.40 which equals roughly 10.60 in 100m (long sprinters should maybe add a tenth or two). The 21.40 time was when he was mainly a 400m runner though.
There are probably more examples. I'd say many elite 800m runners can probably run the 100m around low 11. The more sprint-oriented 800m runners can probably run 11 or slighly below, especially with some sprint training.
Andreas Kramer incorportated more sprint training during the winter season some years ago. Aside from that he's said that he trains a little bit like a distance runner during the winter, with a fairly high amount of mileage. It would'n suprise me if he by that means at least 70 miles per week, but that's only my guessing. I think it's more likely that he can run sub 30 in the 10 km. In the 100m it depends on the start. This is the reason why many ask 800m runners (that aren't elite) what they can run in the 200m on the one hand and 1500 or 3000k on the other hand. In the 200m the start is important but not as important as in the 100m.