How about this? Please think of this as just one of several answers.
Modified formula:
=IF(A1="","",JOIN("",ARRAYFORMULA(REGEXEXTRACT(SPLIT(A1," "),"\b[\w]"))))
- When the cell "A1" is empty and not empty,
""
and the first letters of each word are put, respectively.
- Split the value to each word using
SPLIT
.
- Retrieve the first letter from each word using
REGEXEXTRACT
and ARRAYFORMULA
.
- Regular expression of
\b[\w]
was used.
- Join each array using
JOIN
.
Result:

References:
If this was not the result you want, I apologize.
Added:
As an other, it uses LEFT
instead of REGEXEXTRACT
.
Modified formula:
=IF(A1="","",JOIN("",ARRAYFORMULA(LEFT(SPLIT(A1," ")))))
Reference: