Find number before and after "x"

actually it isn't about it being at the end it is because you have numbers before AND after the "x" so both of the above come back with "2000 5" and because of that it isn't a valid result.
IF "x 3" is valid but "3 x" is NOT valid then this will work:

=LET(in,A1, tag, "x",
notvals,IFERROR(TEXTSPLIT(in,HSTACK({",","."},tag,tag&" "), CHAR(SEQUENCE(10, , 48)), 1),CHAR(1)),
tagVals,TEXTSPLIT(in, notvals,,1),
vals, SUBSTITUTE(FILTER(tagVals,ISERROR(--tagVals),""),tag,""),
out,IFERROR(INDEX(FILTER(vals,NOT(ISERROR(--vals)),0),1),0),
out)

note, YOU can customize this.  The part in line 2: HSTACK({",","."},tag,tag&" ") are all the non-number exception that should be included where tag is defined as "x" in line 1.  So in this version I allow numbers (including decimal and commas) next to "x" or after "x" with a space.  You can 'play' with this by changing the "out" on line 6 to "tagVals" to see what it finds as 'tagged values in the string' or to "vals" to see which of those 'tagVals' it thinks are potential after removing actual numbers and removing the 'tag' value and then finally 'out' which then returns the 1st found 'vals' that is valid number.