Documentation/essential prep for ILR through the Global Talent route

I intend to combine my previous Tier-2 period & my current Global Talent visa period (3 year qualifying period) when applying for my Indefinite Leave to Remain (ILR) in mid-2022.

For the English language requirement, I have a PhD from a UK university, and have the degree certificate to prove that. I understand that I also need to pass Life in the UK (LIUK) test, which I intend to attempt soon. I shall also produce a letter from my former employer saying that I worked in my expert field linked to my original GTV grant and earned a salary for 6 months (I am currently unemployed since my postdoc contract with the UK University ended).

Is there any other requirement for ILR application through the 3-year GTV route? (I note that people here have asked about getting letter from employer about being in their employment for the foreseeable future, P60s, tax forms etc, and also about passport entry/exit stamps.)

An employer letter is not required at all

https://assets.publishing.service.gov.u ... gov-uk.pdf