I've tried using the fix in https://tex.stackexchange.com/a/492197/193767
in order to make TikX's remember picture feature usable, Code below, just
in case:

\unprotect% This fixes the present
bug\unexpanded\def\pdflastxpos{\numexpr\clf_lastxpos\relax}\unexpanded\def\pdflastypos{\numexpr\clf_lastypos\relax}%
This might be needed if you run PGF 3.1.3% see
https://github.com/pgf-tikz/pgf/issues/675\def\XC@tgt@mod#1{#1}\def\XC@sdef#1#2{\edef#1{#2}}\protect\usemodule[tikz]\starttext\starttikzpicture[remember
picture]
     \node (A) {Node 1};\stoptikzpicture
Hi world\starttikzpicture[remember picture]
    \node (B) {Node
2};\stoptikzpicture\starttikzpicture[overlay,remember picture]
    \draw (B) --++(0,0.5) -| (A);\stoptikzpicture\stoptext


However, the following appears:

l.1 6

120806

\lastxpos ->\clf_lastxpos

<write> \noexpand \pgfsyspdfmark {pgfid1}{\the \lastxpos

}{\the \lastypos }

<inserted text>

}\endwrite

<argument> \shipoutscratchbox

\page_shipout_box #1->\clf_shipoutpage #1

\relax \setbox #1\emptybox \global ...

...

l.20 \stoptext


I use LuaTeX 1.10 7127 + ConTeXt MkIV 2019.03.21 21:39 (TeX Live version),
in case this helps. Is another fix necessary? A Metapost alternative would
be fine, too.