There is no other book, Shogun was a stand-alone novel. While there were 2 other novels that formed a rough trilogy they had nothing to do with each other except being set in Asia. Taipan was a book about what was to become Hong Kong and was set a century or 2 after Shogun, and King Rat was about Allied POWs in a Japanese POW camp during the waning days of WWII.
Furthermore, there's not that much more that happens after the events of Shogun, at least nothing that would make for exciting TV. The only other thing of note is the Battle of Sekigahara which, spoiler alert, Toranaga/Tokugawa wins. That was the last major battle of the Sengoku jidai (a period of over a century of near constant civil war) and essentially marked the beginning of the Edo Jidai, a period of long-lasting peace and the Tokugawa shogunate. So there's nothing else that would make for a compelling show unless they completely ignored history and just made stuff up out of whole cloth which would likely end up not being half as good as Shogun was.