The layout is controlled in

https://github.com/openboard-team/openboard/blob/master/app/src/main/res/xml/rowkeys_qwerty2_left5.xml

I think it needs the code

<switch>
   <case latin:countryCode="GB">
      <Key
        latin:keySpec="d"
        latin:keyHintLabel="£"
        latin:additionalMoreKeys="£"
        latin:moreKeys="!text/morekeys_d" />
   </case>
   <default>
      <Key
        latin:keySpec="d"
        latin:keyHintLabel="$"
        latin:additionalMoreKeys="$"
        latin:moreKeys="!text/morekeys_d" />
   </default>
</switch>

@edent you where in the right path but currencies are actually handled in a dedicated common key style, see app/src/main/res/xml/key_styles_currency.xml.
The issue surprises me because from what I see everything looks ok, and nobody reported this so far.

@MajeurAndroid The currency key on the symbols panel is correct.

But what I'm talking about is the key on the main keyboard. The D key looks hard-coded to be $ no matter what the user's locale is.

@edent oh my bad, we are talking about 'more keys', sorry for that.
Yes definitely, I noticed this some time ago, but I could not find an elegant way of localizing only this attribute, to implement something every locale benefits from.
If you manage to do this, feel free to open a PR :)

I think there are two ways to do this.

The first is the code above added to the qwert2_left5. You could also expand it with other locales. For example, India uses QWERTY and their currency is ₹, and Ireland uses €:

<switch>
   <case latin:countryCode="GB">
      <Key
        latin:keySpec="d"
        latin:keyHintLabel="£"
        latin:additionalMoreKeys="£"
        latin:moreKeys="!text/morekeys_d" />
   </case>
   <case latin:countryCode="IE">
      <Key
        latin:keySpec="d"
        latin:keyHintLabel="€"
        latin:additionalMoreKeys="€"
        latin:moreKeys="!text/morekeys_d" />
   </case>
   <case latin:countryCode="IN">
      <Key
        latin:keySpec="d"
        latin:keyHintLabel="₹"
        latin:additionalMoreKeys="₹"
        latin:moreKeys="!text/morekeys_d" />
   </case>
   <default>
      <Key
        latin:keySpec="d"
        latin:keyHintLabel="$"
        latin:additionalMoreKeys="$"
        latin:moreKeys="!text/morekeys_d" />
   </default>
</switch>

There are a few other QWERTY countries which use different currencies. But that would be a start.

Alternatively, you could put the logic in app/src/main/res/xml/rowkeys_qwerty2.xml

I'm happy to send a PR for the first one, if you like - although I don't have the means to compile and test.

This would be great to have. Is there anything I can do to help? I'm not an Android developer, however I could test an alpha version.