Open first sheet keyboard shortcut?

is there a shortcut to open the first sheet? The closest ive found is “Ctrl+Page Up” which Moves one sheet to the left, but I want to move to the first sheet instead Shortcut Keys for Spreadsheets - LibreOffice Help

I’m afraid you will need a little macro and assign it to the preferred shortcut via >Options>Customize>>Keyboard.
The following macro would do what you want:

Sub makeFirstSheetActive()
On Local Error Goto fail REM Will exit if you call the macro for a non-Calc document.
doc = ThisComponent
cCtrl = doc.CurrentController
cCtrl.setActiveSheet(doc.Sheets(0))
fail:
End Sub

many thanks! So if you wanted to open 2nd sheet you’d change it to (doc.Sheets(1)) am I right?

That’s right. The internal sheet indices are 0-based.
If you want to make a sheet active based on its “ordinary” 1-based number instead of its name (for which purpose there is the >Edit>Select>Sheets... menu path), you can use
zeroBasedSheetIndex = -1 + InputBox("Enter the 1-based number of the sheet:", "Select next active sheet by number", 1).
The default number (1 above) you may replece by a different constant or by a variable/expression …

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Sub Plan1
dim plan(0) as new com.sun.star.beans.PropertyValue
plan(0).Name = "Nr" : plan(0).Value = 1
CreateUnoService("com.sun.star.frame.DispatchHelper") _
.executeDispatch(ThisComponent.CurrentController _
.Frame, ".uno:JumpToTable", "", 0, plan())
End Sub