i have ADHD! I've learned that the name of the game is to introduce DELAY and FRICTION in the short term, and work out ROOT CAUSES in the long term.
there's an app called one sec which BLOCKS all other apps on your phone. It can also restrict specific apps. It injects a delay in opening the apps - you can customise the message and delay length.
Android (One UI, maybe just samsung, I'm not sure) phones have settings that can whitelist specific apps during specific times or when a particular "mode" is active. This is under Modes and Routines.
In my experience these are the only ADHD apps that work.
More ADHD pro tips: uninstall as many apps as possible
Set your browser to close tabs automatically after a certain amount of time inactive (mine is 7 days I think). If you REALLY need the open tab, bookmark it.
If you really need the delay, set your phone/ computer browsers to clear cookies daily. This will force you to need to log in to websites every day. This introduces DELAY and FRICTION between you and the easy, habitual distractions.
DELAY and FRICTION are short term solutions. The habits run pretty deep and humans can get used to anything; you'll figure out ways to go around the blockers you put in place in time, and you'll need to create new blockers. Use the time to address the longer term ROOT CAUSES, because that's what's gonna actually make it stick.
ROOT CAUSES is harder. What would you rather be doing, if you weren't on your phone? Journal. Journal a lot. Take long solitary walks (LEAVE PHONE AT HOME!) and try to figure out what you really think, what you really want, when you're not on your phone.
I find I tend to use the phone to Escape. I have worked pretty hard to build a life I don't always want to escape from, as well as some mindsets. I know another very common mode is Seeking, and whatever you're trying to find in Phone chances are it's not there.
You need to retrain your brain to try looking somewhere other than Phone for whatever you're Seeking. This is hard. Might take forever, might never entirely break the habit. But the degree and frequency of me being on my phone for way too long has reduced a lot, in a relatively quick timeframe (1-2 weeks). Don't let slips become slides here.