Question 1: Which is a better strategy: to buy them in RRSP/ RLIF or non-registered account?

A covered call strategy essentially converts capital gains to distributions. This is better held in a registered account. The taxation of covered call instruments can get complicated, and the distributions are taxed as income anyway.

Question 2: How safe do you think is the investment considering these ETFs are technology stocks which have taken heavy beating in recent months. I could not find anything in value stock such as Home Depot.

I think that investing in any single stock is risky and the only one on that list I'd consider is Berkshire Hathaway because it's not really a single stock. Investing in a covered call instrument is risky as well. During an extended market downturn, they will engage in return of capital to meet the target payout. That cannot be sustained forever because it eats away at assets under management, and the bottom can fall out quickly. If I were a retiree, I wouldn't have more than 25% of my income coming from a covered call fund.