If he is not interested to hold his toys then what about holding food such as steam bb carrot, apple, etc. I wont be worried that much as he is already holding just not 2 hands. As for crawling, different babies have different timing to reach their milestones; some v early while some delay.
Get something he has not seen before n can make some noise infront of him. Gradually increase distance for him to reach. He will slowly begin to be motivated to crawl.
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