How can I draw a line segment from an anchor node inside a pic?

I’m trying to draw a line from an anchor node inside a configurable object constructed as a TikZ pic, but it doesn’t work. Is there an explanation and solution for this?

documentclass[10pt]{standalone}
usepackage[siunitx,american, RPvoltages]{circuitikz}  

begin{document}
% --- Manômetro ---------------------
tikzset{pics/manometer/.style={code={
      tikzset{manometer/.cd,#1}
      defpv##1{pgfkeysvalueof{/tikz/manometer/##1}}% local object variable
      %------------------------------
%--- case
  filldraw [thin,fill=pv{case color}, opacity=0.95] (0,0) circle (2.05cm); 
  draw [semithick, white,opacity=0.95] (0,0) circle (1.85cm); 
% --- Tubo de Bourdon interno
  pv{bourdon}[double=white, line width=0.5pt,double distance=2mm,opacity=0.95, rounded corners, cap=round] (-90:1.95) --++(90:0.5) arc(270:20:1.4cm) coordinate(ptb);

  pv{bourdon}(ptb) -- (0,0);
  filldraw[black,thin,fill=white, opacity=0.9] (0,0) circle (1.8cm); 

% --- pressure port node for an external reference
  node (-port) at (0,-1.78){} ;
%--- escala
  foreach angle / label in 
    {225/0, 200/10, 175/20, 150/30, 125/40, 100/50, 75/60,  50/70, 25/80, 0/90,-25/100 } 
  { 
    draw[line width=1pt] (angle:1.6cm) -- (angle:1.8cm); 
    draw (angle:1.3cm) node{textsf{label}}; 
  } 

  draw (-90:0.75cm) node{SI{}{kilopascal}}; % unidade

  foreach angle  in {225,222.5, ..., -25} {draw[thin] (angle:1.7cm) -- (angle:1.8cm);} 
  foreach angle  in {225,212.5, ..., -25} {draw[thin] (angle:1.65cm) -- (angle:1.8cm);} 

  draw[circle,ultra thick,-latex] (0,0) to[short,*-](225-pv{value}*2.5:1.1cm); % Valor indicado 
  draw[fill=black,rounded corners] (0,0) -- (225-pv{value}*2.5-30:-5mm) -- +(225-pv{value}*2.5-90:5mm) --  cycle;

  node[draw,circle, fill=gray!10, opacity=0.85] at(0,0){};
    }
  }, % end of code
  manometer/.cd,
  value/.initial=30,
  case color/.initial=cyan!60!gray,
  port color/.initial=green!30!black,
  pressure port/.initial=draw, %path % to hide pressure port
  bourdon/.initial=draw, %path % to hide bourdon tube
} % End of Manometer

begin{tikzpicture} 
% defining a pic with name P01
% The problem is that the connection port is outside of the object.
pic [local bounding box=P01] at (0,0) {manometer={value=50, port color=olive!50!gray, pressure port=draw, bourdon=path}};

  draw[color=green!50!black, double=cyan!1, line width=2mm, double distance=1mm, opacity=0.95, rounded corners] (P01.-90) --++(0,-1) --++(-2,0) ;


%--- Following is the desired method using an internal node reference  to connect the object but  the following error occurs:
% Package pgf Error: No shape named `pgfcirc@short2122start' is known. ...gray, pressure port=draw, bourdon=path}}

pic (P02) at (5,0) {manometer={value=50, pressure port=draw, bourdon=draw}};
draw[color=green!50!black, double=cyan!1, line width=2mm, double distance=1mm, opacity=0.95, rounded corners] (P02-port) --++(0,-1) --++(2,0) ;

end{tikzpicture}%
end{document}