You can have DMARC, SPF and DKIM all correctly configured on a clean IP and some mail server at Microsoft will still drop your mails because it's having a hard day and it feels like it.
That place in particular (which I use and can recommend) even have a (permanent?) free tier. ;)
If you're serious about this than go talk to a non-tech person and tell them to self-host email and see how they do. Look at their challenges, build a solution and then offer it.
That's not at all what the conversation is about, and routing through an external place removes a whole bunch of hassle compared to setting up and maintaining outbound email.
You might not like it for some reason, but that's on you.
What's the point? At that stage you've already conceded the deliverability problem so now you're just wasting time administrating dovecot and keeping up with security patches.
Obviously yes. Not sure why you're trying to pretend otherwise.
Good luck with that. ;)