AgGrid access grid data in a CustomRowRenderer

Question

I am using a AGGrid (actually via custom wrapper) and I have checkoboxes on each row. Also, I have a bottom row with buttons. I want to enable/disable the buttons based on selected rows.

<AgGrid
                        id="dataListGrid"
                        containerProps={{style: {height: gridData.length * 30, minHeight: 180}}}
                        className="customGrid"
                        columnDefs={dataListColumns}
                        frameworkComponents={{checkboxColRenderer: checkboxColRenderer}}
                        gridDescription="List"
                        onGridReady={handleGridReady}
                        rowData={gridData}
                        enableBrowserTooltips={true}
                        pagination
                        paginationPageSize={100}
                        onCellClicked={onCellClicked}
                        onRowSelected={(params) => {
                              params.api.redrawRows({
                                rowNodes: [params.api.getPinnedBottomRow(0)],
                              });
                            }}
                        isFullWidthCell={(rowNode) => rowNode.rowPinned === 'bottom'}
                        fullWidthCellRenderer={CustomPinnedRowRenderer}
                        pinnedBottomRowData={[{}]}
                        {...props}
                    />   

My data looks like below;

let gridData = [{
            fmIdentifier: 'Test data 1',
            category: 'Test',
            comments: 'Test',
            fm: 'Test',
            gti: 'Test data',
            wins: 'Test',
            identifier: 'Test',
            status: 'Test data',
        }, {
            fmIdentifier: 'Test data 2',
            category: 'Test',
            comments: 'Test',
            fm: 'Test',
            gti: 'Test data',
            wins: 'Test',
            identifier: 'Test',
            status: 'Test data X',
            rowPinned: 'bottom'
        }]
        setDataListColumns(DataListColumns);
        setGridData(gridData);

Below is how my CustomPinnedRowRenderer looks;

class CustomPinnedRowRenderer {
  init(params) {
    this.eGui = document.createElement('div');
// QUESTION : I want to access the grid data here...param.api.data shows empty object {}
    const selectedNodes = params.api.getSelectedNodes();
    this.eGui.innerHTML = finalDOMStr; //finalDOMStr has HTML

  }

  getGui() {
    return this.eGui;
  }

  refresh() {
    return false;
  }
}

My question is inside the CustomPinnedRowRenderer (on row select), I want to check the param.api.data (so that I can accordingly render enabled/disabled buttons)

But param.api.data seems to be empty object for some reason ?

UPDATED

I tried adding the property "checked" to my data model and mapped to checked state as below

let gridData = [{
            checked: true,
            fmIdentifier: 'Test data 1',
            category: 'Test',
            comments: 'Test',
            fm: 'Test',
            gti: 'Test data',
            wins: 'Test',
            identifier: 'Test',
            status: 'Test data',
        }, {
            checked: false,
            fmIdentifier: 'Test data 2',
            category: 'Test',
            comments: 'Test',
            fm: 'Test',
            gti: 'Test data',
            wins: 'Test',
            identifier: 'Test',
            status: 'Test data X',
            rowPinned: 'bottom'
        }]

However, any checked data stays as checked i.e. I cannot uncheck

My checkboxColRenderer looks as below

import React from 'react';

export default (props) => {
    return (
        <span>
            <input type="checkbox" checked={props.data.checked} />
        </span>
    );
};