Add more activities for him so he can keep the 2nd nap. He just growing into a soon-to-be toddler in couple month. You gonna have to add more activities for him to do.
We're only just transitioning to one nap at 18 months. 8 months is probably not impossible but very early. 9-10-month-olds have that pre-toddler energy vibe and you REALLY have to tire them out. Also, a shorter wake window in the morning might help. Get the first nap out of the way early if you can, the second maybe around 1:30-2. Also, and bear in mind I am not assuming anything just mentioning this for consideration, pay attention to what he's eating when he gets like this. We're all very aware of added sugars causing issues but even having a lot of fruit or carby bread / pasta can cause energy spikes. People are always questioning why we don't let my daughter have cakes or ice cream before 2 years of age, and we look at her bouncing off the walls after eating a bowl of fruit and tell them "This. This is why."
my 8m old is on a similar schedule, maybe wake a little earlier and extend the wake windows a bit? might not be ready for one nap but just could stay up between naps a bit longer