Is it possible to enter the US through the Nexus lane while my Nexus card is being renewed? And how?
According to this website, you can use an Expired Nexus card, provided you have submitted your renewal, for up to 6 months after expiry.
"The vetting process cannot be expedited. If you submitted a renewal application before expiration of your current membership, then you can continue to use your benefits until the renewal is finalized (up to 6 months after your expiration date)."
No, it is not. You are permitted to renew as early as one year prior to expiry so there is no need to leave renewal to the last minute.
You can, however, use a non-NEXUS lane as usual, using your passport or other WHTI-compliant identification.