Mycelium is very safe to use to store Bitcoin, in addition to private keys under our control, Mycelium is also safe from online theft.
There is no online wallet with the feature of "being safe from online theft".
If you want to be 100 secure and protect yourself from getting hacked completely, you should generate your wallet on an airgapped device and your keys never connect to the internet. Otherwise, there's always the possibility of getting hacked.
A good wallet allowing you to generate the wallet and spending the fund offline is Electrum. I doubt that's possible in Mycelium. Someone correct me if I am wrong, please.
This is true, online wallets always carry a risk and people need to realize that, because at the end of the day there is a good chance that we could end up with something that will be a hacking or maybe rug pull or maybe a failure, whatever it is, there is always a chance that if your money is not in your own wallet, and in something else, then it could be stolen and we shouldn't be risking it.
Just get a ledger and put it in there if it is too much, of course not needed if you have only 50-100 bucks, but if you go over a certain amount where it is like over a few months salary worth, then it would be a lot better idea to just buy a ledger or trezor to keep assets safe.
