ipywidgets file browser based on the Select widget. Single click folders to enter, click Load to load a file.

ipywidget_file_browser.py

import ipywidgets as widgets

import os
from pathlib import Path
cwd = Path(os.getcwd())

FOLDERLABEL = '-------FOLDERS-------'
FILESLABEL = '-------FILES-------'

def get_folder_contents(folder):
    'Gets contents of folder, sorting by folder then files, hiding hidden things'
    folder = Path(folder)
    folders = [item.name for item in folder.iterdir() if item.is_dir() and not item.name.startswith('.')]
    files = [item.name for item in folder.iterdir() if item.is_file() and not item.name.startswith('.')]
    return [FOLDERLABEL] + sorted(folders) + [FILESLABEL] + sorted(files)

def go_to_address(address):
    address = Path(address)
    if address.is_dir():
        address_field.value = str(address)
        select.unobserve(selecting, names='value')
        select.options = get_folder_contents(folder=address)
        select.observe(selecting, names='value')
        select.value = None

def newaddress(value):
    go_to_address(address_field.value)
        
def selecting(value):
    if value['new'] and value['new'] not in [FOLDERLABEL, FILESLABEL]:
        path = Path(address_field.value)
        newpath = path / value['new']
        if newpath.is_dir():
            go_to_address(newpath)
            
        elif newpath.is_file():
            #some other condition
            pass

def parent(value):
    new = Path(address_field.value).parent
    go_to_address(new)
    
def load(value):
    filepath = path / value['new']
    # load using your favourite python software!
    
address_field = widgets.Text(value=str(cwd))
up_button = widgets.Button(description='Up')
select = widgets.Select(options=get_folder_contents(cwd), rows=15, value=None)
load_button = widgets.Button(description='Load')
box = widgets.HBox([widgets.VBox([address_field, select]), widgets.VBox([up_button, load_button])])

select.observe(selecting, names='value')
up_button.on_click(parent)
load_button.observe(load)
address_field.on_submit(newaddress)

box

Comments are very welcome