Do not trust, verify!
Not your keys, not your coins.
So... exchanges, ETFs and Saylors have as much coins, as they publicly proved their addresses. Else it's just charlatanery.
It takes a bank 3 years and about 4000 man days to implement a Bitcoin (and shitcoin) trading and custody solution in the tradfi software.
Remember, this have to be paid.
16 years, devs paved the way so you can have your #Bitcoin solution with just 12 words... for free.
Who's selfhosting an email server? What are you using? How do you stay off blacklists? How much time do you spend on maintenance?
After 10+ years, I want to give it a try again...