I use a small locking weekly pill organizer . Just put one of each pill in each day's compartment. It's lightweight, it stays locked, and it's thin even if it's on the longer side.

Try looking for childproof ones or metal ones... like these

https://www.amazon.com/dp/B001G3SXYK/ref=cm_sw_r_cp_apa_glt_fabc_DZFXZH83P5S5MV8FWTWY

https://www.amazon.com/dp/B08XMJF6PB/ref=cm_sw_r_cp_apa_glt_fabc_PBWKRMV9YAX6GTKWMQJQ?_encoding=UTF8&psc=1

Something like this? https://www.amazon.com/Locking-Organizer-Prescription-Medications-Assorted/dp/B001G3SXYK/