certification for US residency: Form 8802 line 4a and line 10

I am trying to request a certification for US residency in 2021 (form 6166).

As I understand I need to file form 8802 for that. I got it mostly done, but just can't wrap my head around a few points (the instructions seem unclear and I am finding conflicting info).

Any hints much appreciated!

l. 4: Applicant is (check appropriate box(es)):

a) (✓) Individual (ok that was easy!)

But then I am unsure about what individual I am. Does "current nonimmigrant status" refer to the tax year I want the certification (2021), or the actual current year (2025)? And does "Date of change" correspond to changes within the year I want the certification, or later changes?

I came to the US in 2018 on a J1 visa (and was in the US for almost all of the time each year since then), switched to H1-B in 2022, and got a green card in 2025. So what I tried is

(✓) Other U.S. resident alien. Type of entry visa: J1

Current nonimmigrant status: U.S. lawful permanent resident (green card holder)

Date of change: …/2025

Does that look right?

Do I need to attach a copy of my green card because I did not file taxes as a green card holder yet?

l. 8: Tax period(s) on which certification will be based

Do I understand correctly, that I just fill in the last month of the year for which I want the certificate? That would be:

202112

l. 10: Enter penalties of perjury statements and any additional required information here

Do I understand correctly that this is only needed when the certificate is for a year that has not been filed? Or do I need to fill in a statement?

Thanks!

Edit: one more question: do I need to attach my 2021 tax returns, or not (since they are already filed)?