MacroView Mail allows you to save attachments to SharePoint Online (Office 365) as a PDF file type.
To save an attachment as a PDF in Outlook
Step 1: Open the MacroView Mail App
Open the email in the Microsoft Outlook App and tap the three dots in the top right hand corner of the email.
Then select the MacroView Mail icon.
Step 2: Select the file to convert
Select the 3 dots of the file to be converted.
Click on the 'Save as PDF' icon
Step 3: Select a location to save the attachment.
See below for more details on how to save emails to SharePoint with the Mail app.