It's a phase, it will pass. BOTH my kids did this too, at certain developmental ages.
Now, when he wakes (is he in a crib or do you co-sleep?)... just let him be. There is no reason to rush in, swoop him up, and then be 'awake' too. If he is fine, playing in the crib by himself, then let him be. Just gauge him. IF he then cries/screams/yells or is in distress, then go and get him.
But either way, keep everything dark, keep things quiet, don't turn on any lights, don't talk or just minimally, don't 'play' with him etc. Just keep everything subdued and 'boring.' And just lie down yourself, or on a sofa.
You seem to have a good nap/bedtime routine. It's fine. I would not adjust that or change it. Keep it consistent.
This phase will pass. Really. For babies and toddlers... they go through sleep quirks and sleep pattern changes. But, it will normalize again... and you just have to bear through it. Thus, keeping your nap/bedtime routines the same. Then likewise, it also helps in keeping the child consistent and 'knowing' what to expect.
Both my kids did that. I know how it feels. But, it passes.
Good luck,
Susan