To sum it up shortly:

Owning, Possessing, Selling. Purchasing, Transferring, Transporting an 80% recevier or frame (aka an unfinished reciever or frame) in and of itself is currently NOT against the law BUT Owning, Possessing, Selling. Purchasing, Transporting, Manufactuering or Assembling that 80% reciever or frame into a firearm (or finished reciever or frame) without having it seralized by an FFL beforehand is illegal.

AB 286 did make it law (and is currently in effect and enfoceable) that possessing, manufacturing, assembling, selling, recieving, transporting any firearm or finished reciever or frame without a serial number is illegal in Nevada as of January 1st, 2022 unless specifically excluded in sections 4 and 5 of AB 286 (see below).

According to the Judgment issued by Judge Schlegelmilch of the 3rd Judicial District Court of Nevada in Lyon County, Nevada on December 10th, 2021 only Sections 3 and 3.5 of AB 286 are barred from being enforced... and that of course is only for now, pending appeals by the State of Nevada to the appellate court and/or higher.

The specific sections of AB 286 that are currently barred from being enforced are:

Section 3:

A person shall not possess, purchase, transport or receive an unfinished frame or receiver unless:

(a) The person is a firearms importer or manufacturer; or
(b) The unfinished frame or receiver is required by federal law to be imprinted with a serial number issued by a firearms importer or manufacturer and the unfinished frame or receiver has been imprinted with the serial number.

and

Section 3.5:

1. A person shall not sell, offer to sell or transfer an unfinished frame or receiver unless:

(a) The person is:
  (1) A firearms importer or manufacturer; and
  (2) The recipient of the unfinished frame or receiver is a firearms importer or manufacturer; or (b) The unfinished frame or receiver is required by federal law to be imprinted with a serial number issued by an importer or manufacturer and the unfinished frame or receiver has been imprinted with the serial number.

The judgement specifically states that the decision has no affect on Sections 4 or 5 of AB 286.

These sections provide the following laws:

Section 4:

1. A person shall not manufacture or cause to be manufactured or assemble or cause to be assembled a firearm that is not imprinted with a serial number issued by a firearms importer or manufacturer in accordance with federal law and any regulations adopted thereunder unless the firearm:

(a) Has been rendered permanently inoperable;
(b) Is an antique firearm; or
(c) Has been determined to be a collector’s item pursuant to 26 U.S.C. Chapter 53 or a curio or relic pursuant to 18 U.S.C. Chapter 44.

Section 5:

1. A person shall not possess, sell, offer to sell, transfer, purchase, transport or receive a firearm that is not imprinted with a serial number issued by a firearms importer or manufacturer in accordance with federal law and any regulations adopted thereunder unless:

(a) The person is:
  (1) A law enforcement agency; or
  (2) A firearms importer or manufacturer; or

(b) The firearm:
  (1) Has been rendered permanently inoperable;
  (2) Was manufactured before 1969;
  (3) Is an antique firearm; or
  (4) Has been determined to be a collector’s item pursuant to 26 U.S.C. Chapter 53 or a curio or relic pursuant to 18 U.S.C. Chapter 44.

You can read the actual judgement here: https://www.scribd.com/document/546715831/AB286-District-Court-rules-in-favor-of-Polymer80?fbclid=IwAR11NlF2YvZCJUYGaPDDguT5Xpmc4dxbM87fP1I-zNffwWJD8eEkRb811lQ

The Above is Only for Reference and IS NOT to be consider acutal Legal Advice. If You Have Questions that Specifically Pertain to Acutal Laws, seek the gudiance from a licensed attorney.