Diversify portfolio or focus on fewer stocks/ETFs?

I'm 28, and fairly new to the market, with only ~$1100 value of stocks as of now (stocks + ETFs). I would like to continue to keep growing and appreciate some suggestions.

1. Is it worth to have pennies on some stocks? For instance, I invested about $5 in Berkshire Hathaway (BRK.A) back in April 2023, which is now about $7. I never added to this ever since. Does it even make sense to hold this or should I continue to pour in this on a regular basis.
2. Furthermore, my $1100 of portfolio is in 26 different companies (e.g., Apple) and ETFs (e.g., SCHD). My friend was looking at this and told me that this is not the right approach, mainly due to point 1, as there are some stocks where I have little-to-no investment. So, what would be the more effective approach here: (a) focus all my money on fewer stocks and ETFs (if yes, is there a number)? or (b) am I doing it right by diversifying, regardless of how much I put in each of those.

My background: I started investing in January 2023 and until December 2024, I had only $500 worth of investment. In December 2024, idk why but I gained *a lot of* interest and poured $700 in different stocks and ETFs. My new year resolution is to invest regularly and on schedule.