As the SX126x chips consume depending on configuration 4 - 10 mA in receive mode, this simply isn’t going to happen.
The only way you can achieve your goal is to make reception non-continuous but rather limited to brief windows in time when you activate the receive preamble detector and see if there is a message; if there isn’t, you then go right back to sleep.
This requires time coordination between transmitter and receiver. Battery powered LoRaWAN nodes do it by means of the LoRaWAN contract, which says that reply transmissions are sent (depending on mode) precisely 1 or 2, or 5, or 6 seconds after the end up the uplink they are in reply to. So a node transmits whenever it likes, but only listens at two very brief points in time afterwards. All of that works, because the battery powered nodes are in communication with an always-on mains-powered gateway.
This is more challenging when it is the receiver which is battery powered. One approach is to have a mains powered transmitter which sends beacons frequently enough that a receiver can be put in an always-on “pairing” mode and by listening for no more than a minute, detect one of these unsolicited transmissions.
Once you have one transmission, with a known interval you can know when to wake up the receiver and try for the next - basically the expected time minus to plus an error allowance. If you don’t get the next transmission, then you try again at the next opportunity, but listen for longer as your error allowance must now be doubled. And then tripled. If you fail to get anything enough cycles in a row, at some point you have to declare failure and give up. Maybe you do nothing overnight and trigger another pairing attempt the next day on the theory the transmitter has been repaired; maybe you assume it has been taken out of service and don’t try again until pairing is manually re-triggered.