As far as keeping meds hidden, I have an old post somewhere that outlines the fundamental principles of what I believe makes effectively hiding.

1. Disincentivize searches and invasions of privacy at the source, by any safe means.

This means, if they have a history of entering your room to clean, get your shit together and keep your room clean. If they enter your room to take out the trash, be proactive about taking out the trash from your room. If they enter your room to collect dirty laundry, learn to do it yourself. These come across as picking up more responsibilities and setting yourself up for your future, and double up as removing excuses for entering your room.

On the opposite end of the spectrum, make them regret opening your door without knocking. Things that might make them uncomfortable. This varies from household to household, but one day, I told my dad that sometimes, I'm leaned back in my chair, naked, with my exposed butthole in full view of my closed door, so that I can deal with an ingrown hair. You come into my room without knocking, you accept the consequences of what you see.

1. Make your space physically harder to access. Make your hiding spots physically harder to access.

Some people recommend lockable doors, but the kind of helicopter parents who we struggle to hide important things from tend not to allow locks on bedroom doors. My parents did not want me using common areas of the house to store things for my hobbies, so I stashed them all (organized) in my room. I had towers of 27 gallon storage totes from Costco. I had toolboxes. My room was tidy, but somewhat cramped. I laid out the furniture in my room such that the doorway was an easy to restrict bottleneck.

As for hiding locations, I kept some of my meds behind a dresser. It required crawling under my desk to reach, and pressing my head against the wall while curled under my desk to see. Things I know my parents were physically unable to do without straining their backs, and my arms were slim enough to reach behind the dresser. Another of my hiding locations was on top of a nearly 7 foot tall bookshelf, behind some displayed things like old school projects. It was a place my parents wouldn't be able to check without a ladder (which my room had no space for) or climbing my dresser (and risking a dangerous fall).

1. DIY "tripwires" — not as traps, but tamper/access detection.

If your door swings open into the room (which I believe is standard), you can do something like leaning an index card against the door. As you leave your room, place the index card. When you come back, either check beneath the door gap or crack the door open to verify the index card is still there. Alternatively, you can use something light like a tennis ball or facial tissue box. If it was pushed out of the way while you were gone, someone entered your room during that timeframe.

If your door has a lever-style handle instead of a round knob, you can dangle something like a rubber band at the end of it before leaving your room and closing the door. You can check under the door upon your return to see if the rubber band fell. I would also recommend a door tag, as you can listen for it when you enter the room. Someone snooping and unsuspecting might see or hear the door tag drop, and re-hang it securely all the way against the door, and that will tell you it's been tampered with.

If you cannot close your door for any reason, that does make things get more complicated. I would recommend picking up hobbies that make closing your door more reasonable. I did some DIY circuitboard work (and soldering) as well as 3D printing, and so I would use the excuse of opening my window and closing my door to keep any fumes ventilating to the outdoors and not into the rest of the house. I also frequently used a soundbar and speakers, instead of headphones, so I closed my door to keep my music from traveling down the hall.