These apps work only if your Chromebook is updated to Chrome OS v53 or newer.
The Chromium Projects keeps alist of supported Chrome OS systems that can run Android apps.
Best web client Alternative: Firefox Focus
Blocks website trackers.

Unsplash
Completely erases browsing history.
Faster page load times.
Can cause computer battery to drain faster.

But an added feature is the speed with which pages load on the Firefox Focus net web surfer.
Best Task Tracker: TickTick To-Do List
Easy to add to-do list items with deadlines and reminders.
Some features hidden behind paywall.

Custom notifications may not alert you to a deadlined task.
Status function can be a little laggy.
The TickTick To-Do List is an improvement over the Google Tasks list that’s standard on Chromebooks.

Backup Assistant to help backup all the data you don’t want to lose.
Sort and categorize files in a way that’s convenient for you.
App collects usage data that doesn’t need to be collected.

Can be buggy immediately after updates.
Astro gives you a single place to store and manage your files.
Stream radio and podcasts.

Requires a subscription after free trial ends.
Ad heavy, even with paid subscriptions.
Take Notes & Markup PDFs: Squid
Ability to capture handwritten notes.

Combines gestures with stylus or active pen for more control.
Lots of page templates to choose from.
Can open and edit PDFs.

Limited text formatting capabilities.
No ability to convert handwriting to text.
Squid is a great little program for taking handwritten notes that lets you use your stylus or active pen.
Another great feature is the sharing capabilities included with Squid.
Share your notes or store them in the cloud.
Includes an OAUTH2 authorization feature for some mail providers.
Integrates with cloud storage for backups and restores.
Allows access to POP and IMAP email accounts.
Free version is ad heavy.
Forces you to use “sent with Aqua Mail” signature line.
The default email app on a Chromebook is fine.
It does most of what most users need.
More than 60 photo filters.
Body editor for slimming faces and bodies.
Limited facial editing features.
Some features hidden behind a paywall.
Polish is a full-featuredphoto editorfor Chromebook offering tons of filters and great features.