MuseScore 3 also reads the arpeggios spanned in two staves also in the same way of Dorico. I do not know how the recent version of exports it… However, the following is the musicXml text of the first bar in the attached picture (measure number = “11”):
<measure number="11" width="162">
<print new-system="yes">
<staff-layout number="1">
<staff-distance>102</staff-distance>
</staff-layout>
</print>
<note default-x="65">
<pitch>
<step>D</step>
<octave>6</octave>
</pitch>
<duration>16</duration>
<voice>1</voice>
<type>half</type>
<stem default-y="-45.5">down</stem>
<staff>1</staff>
<notations>
<arpeggiate default-x="-22" number="1"/>
</notations>
</note>
<note default-x="65">
<chord/>
<pitch>
<step>G</step>
<octave>6</octave>
</pitch>
<duration>16</duration>
<voice>1</voice>
<type>half</type>
<stem>down</stem>
<staff>1</staff>
<notations>
<arpeggiate default-x="-22" number="1"/>
</notations>
</note>
<note default-x="65">
<chord/>
<pitch>
<step>D</step>
<octave>7</octave>
</pitch>
<duration>16</duration>
<voice>1</voice>
<type>half</type>
<stem>down</stem>
<staff>1</staff>
<notations>
<arpeggiate default-x="-22" number="1"/>
</notations>
</note>
<note default-x="124">
<pitch>
<step>D</step>
<alter>-1</alter>
<octave>7</octave>
</pitch>
<duration>8</duration>
<voice>1</voice>
<type>quarter</type>
<accidental>flat</accidental>
<stem default-y="-20.5">down</stem>
<staff>1</staff>
</note>
<backup>
<duration>24</duration>
</backup>
<note default-x="65">
<pitch>
<step>D</step>
<octave>5</octave>
</pitch>
<duration>24</duration>
<voice>3</voice>
<type>half</type>
<dot/>
<stem default-y="15.5">up</stem>
<staff>2</staff>
</note>
<note default-x="65">
<chord/>
<pitch>
<step>G</step>
<octave>5</octave>
</pitch>
<duration>24</duration>
<voice>3</voice>
<type>half</type>
<dot/>
<stem>up</stem>
<staff>2</staff>
</note>
<note default-x="65">
<chord/>
<pitch>
<step>B</step>
<alter>-1</alter>
<octave>5</octave>
</pitch>
<duration>24</duration>
<voice>3</voice>
<type>half</type>
<dot/>
<accidental>flat</accidental>
<stem>up</stem>
<staff>2</staff>
</note>
</measure>