The smallest current vaguely mainstream phone IMO is the Asus Zenfone 10 at 146.5 x 68.1 x 9.4 mm. The iPhone 13 mini is 131.5 x 64.2 x 7.65mm. Then you have weird stuff: https://www.gsmarena.com/results.php3?nYearMin=2022&fDisplay... so perhaps by the time your phone dies the Cubot Pocket 4 or 5 will be your answer. Here's the Pocket 3: https://www.gsmarena.com/cubot_pocket_3-12314.php