Unable to find ATtiny841 anywhere readily available.
Is there any way out of this?
AliExpress is likely your only option right now. They are backordered from most suppliers otherwise.
How about other ATTINY alternatives? For Example I see available ATTINY424, but they have smaller Flash and EEPROM memory. 4kB flash and 128b EEPROM instead of 8kB and 512b.
How much do the cell modules need?
Memory more than 7.
I have about 200 ATTINY841.
But it wont help you. I´m in germay