I know that Ledger sells the required cables in their shop. They call it the
Ledger OTG Kit. Wouldn't that be enough to pair Electrum mobile and a Ledger hardware wallet?
It's a set with three different cables:
USB-C to Micro-USB
USB-A to Micro-USB
USB-C to USB-C
The price is ridiculous - €15, but cheaper alternatives can be purchased in tech shops.
Electrum currently does not communicate with any USB devices on their Android version. You need some sort of interface code to be able to communicate with it in the first place. Implementing that first would be the first step in supporting HW wallets, which AFAIK is in the pipeline.