A considerable number of key elements are currently missing as per https://techcommunity.microsoft.com/t5/outlook-blog/outlook-on-your-mobile-browser-is-being-upgraded/ba-p/1125816

This includes the ability to:
Choose “from” address while sending an email message
Save or Add attachments from cloud locations including OneDrive
View shared calendars

All of which are coming soon.

However key functionality will be unavailable as there are no plans for it:

No option to set message sensitivity & importance
Set sensitivity and importance to specific message sent
No voting buttons
Read receipts
No option to apply retention policies
No access to add-ins
No ability to view shared folders and shared mailbox in folder list
No Calendar search
set email reminder for events
No support for adding or searching for people’s calendars
No ability to add groups’ calendars
No option control from Settings which events from your email are automatically added to your calendar

I have looked and looked and I can't find the Notification option on my Mobile app for Outlook 365 to save my life. My phone does not receive notifications when I get emails. I have to check my inbox frequently when I'm expecting an email because it will not send me notifications. I've googled the problem and I've visited the help center, all of which have directed me to a notifications option under the settings drop-down. There's just one problem... there's no such option under my dropdown. I've looked through every setting or personalization option available on the mobile app and have seen nothing pertaining to notification settings. Please advise where this notification setting option is on the mobile app because it doesn't appear under settings, nor under any of the listed settings options on mine

Throughout all the various redesigns, the frontend team seem to have lost track of the fact that some people want to (or need to) verify the link target of a hyperlink contained in an email before opening the site.

This is just good security practice. Spam filters are not going to catch everything.

Also, what if I want to share that link in some other app, again, with a long press? You've disabled that as well.

Yes, binding scroll events and taps precisely is a challenge on the web platform. You are clever people and I'm sure you can figure it out. Plenty of other mobile web sites do.