You are right. This reason made me say that storing large amounts of bitcoin assets in a wallet like Bluwallet and a number of other wallet choices that have a good reputation are a problem that must be carefully thought out.
Because OP said that he could not operate a PC smoothly only able to use the smartphone well, the attention of the vulnerability of the installed device was worthy of attention related to the security.
Well, if the Andriod devices are not safe to install the bitcoin wallet, the laptops / Desktop aren't safe too. Any device which is connected to the Internet increase the chances of getting vulnerable to malwares / hacks etc.
The large amount of bitcoin should always be stored on the hardware wallet or on the Air gapped devices (for those who are techy and understand how to setup and operate).
You should only use wallets like Electrum or blue wallet only for the purpose of storing small amounts of bitcoins that you want to transact with. The right place to store the majority of your long term savings are the hardware wallets.