FlyerTalk Forums - Cheapest way to extend choice points expiration

Choice points expire after 18 months of inactivity. The Choice FAQ lists ways to extend the expiration date:

Qualifying point-eligible stay. Must check-in
Redeeming for free nights (warning: don't touch or cancel the reservation)
Redeeming for gift cards
Redeeming for other awards : miles, cruise, magazines, golf, donations
Earning points with the Choice Mastercard (and presumably the Visa, not currently available)
Referring a friend who completes a points-eligible stay (the post date is used, not the referral date)
Purchasing points
Gifting points counts for the recipient only. (Listed further down in the FAQ.)

Activities that do not officially extend the expiration date but are confirmed as working.

Dining "Eat and Earn" (confirmed working)
e-Rewards (confirmed)
Transfer from Amex Membership Rewards to Choice (confirmed working 3/2023, despite terms)
Transfer from Citi Thank You points to Choice (confirmed working)

Activities that do not officially extend the expiration date. Unknown if they actually work. Please post if you find otherwise:

Does not work, confirmed:

Redeeming a cash+points stay and then cancelling to effectively "buy" points
Choice Shopping Mall, 1800Baskets, 1800Flowers, and Quicken Loans programs are discontinued

Other notes:

You can redeem points for an award dated past your points expiration. If you cancel though, expect to lose points.
Radisson Americas has a 24-month expiration policy.
Choice earning page