Normally I won't leave a one-star review, but in this case my frustration and time loss exceed everything experienced so far. Three hours wasted time not only mean overtime work, but also a financial loss way beyond the highest tier's pricing.

Sidekick claims to be "a productivity browser for focused work", make workflows faster etc. etc.
Under the hood, it seems to be derived from Brave and Chrome (at least partially, see https://github.com/pushplaylabs).

At first sight, the browser seems to be a real productivity killer:
- global search through all open tabs, history etc.
- session switching
- auto-unload tabs
- multi-profile applications (e.g. one GMail icon, but different accounts at the same time)
- Anti-distraction/ADHDS-sensitive features
- Pre-video session notifications
- Speed (claims to be 3 times (!) faster than vanilla Chrome)

Alas! It seems to me these claims were more related to aggressive marketing than real-life proof. Working in an enterprise environment (SSO), I gave up after three hours (I really wanted to give this software a chance). I do a lot of reasearch and normally have around 10-50 tabs open in parallel to compare and relate information (synchronoptic reading, cf. Adler/Van Doren) in a topic-specific session (of which I have normally 5-10 in parallel, so organizing around 500 up to 1K tabs in parallel isn't uncommon for me). I need to switch the context frequently due to incoming ad-hoc requests. When using a Chromium-based browser, it's Brave and here I fully rely on it's "groups" feature and pinned tabs for web apps that need to be open all the time (i.e. GMail, GCalendar, Slack etc.).

Sidekick seemed to be a perfect match, but couldn't meet my expectations:

At first, I noticed inconsistencies:
- Though I answered the onboarding option to make Sidekick the default browser with no, I got asked this question later on again - from a macOS system window.
- Though I unchecked the onboarding option to start Sidekick during login, I acutally found Sidekick enabled as login item in the macOS system settings.
Both gave me the impression that my choices weren't respected.

Then I noticed things that led me to the further conclusion that there is a gap between promise and reality.
- After reading https://www.meetsidekick.com/privacy-policy/ and https://www.meetsidekick.com/terms-of-use/, I'm deeply concerned what data get's collected and how. Basically this legalese seems to contradict with a modal popup "Sidekick Privacy Principles" during the onboarding process: here e.g. it says it would never share data with 3rd parties, whereas the privacy policy and the terms of use clearly disclaim the do exactly that (e.g. URLs accessed etc.).
- The "Sidekick help" from the menu is just the Google Chrome help - there are some pages linked to their Intercom account, but they weren't helpful and didn't answer my questions.

And finally I stumbled upon functionalities that finally killed my productivity:
- Even after disabling all private mode, auto-suspend etc. settings, I was forced to log in to the various accounts (Slack, GMail, both w/ SSO) each time I switched back (not: reopened) to the according application tab (which basically seems to be like a pinned tab). That's a complete productivity killer for me as I switch back to specific tabs frequently (such as GMail) and don't want to loose time by looging in again and again.
- Deleting an account doesn't seem to be possible and recreating one with the same e-mail neither.
- So it seems after having decided to use an account in "privacy mode" (needed for the "one application - multipe accounts" feature), it isn't possible to switch this mode off.
- Groups from Brave weren't imported via the import.
- Following https://www.humanetech.com/take-control, the approach to just block addictive pages for a while, doesn't make sense to me at all: Either you switch off all notifications and remove all distractions, focus on your work and decide on your own when to approach your channels or you stay addicted and distracted. To have short time windows and afterwards be pushed back to distraction doesn't seem to be wise to me.
- I couldn't find a way to make the extension bar appear permanently instead of auto-hiding.

There are many workflows to deal with cognitive load when approaching the internet and I assume, Sidekick is able to support some. My workflow isn't covered at all and the many inconsistencies I stumbled upon, starting from the legal ground up to things as being forced to log in again and again to GMail and GCalendar justify the low rating for me.

Switched back to Firefox + Multi-Account Containers + Sideberry. I guess, investing the refund in Sideberry will be a good choice.