For that you will have to use a form. There's no other way currently to upload and show attachments from SharePoint.

If you add a form, link it to your SharePoint list and add the field 'Attachments' in edit fields. In the 'Item' property of the form, you can add the certain item for which you want to show or edit attachments. For example if you have a gallery with SharePoint items (from the same SharePoint list), you can do:
Item: gallerySharePointListItems.Selected
This way it will show the attachments of the selected item that are in the list. If you want to add an attachment, you can then for example in a button submit the form:
SubmitForm(frmAttachmentsSharePointList)
You can of course add multiple fields to update multiple fields in the list.
However, the way I rather do it is with a form with solely only the attachment as field and use Patch instead. This gives you more control on the updates. When you want to edit the item and attachments to the item, you can do it like next:
Patch(
'CP Notes_1',
LookUp('CP Notes_1', ID = varCurrentNote.ID),
{
Title: cbNoteTeamEdit.Selected.Value & " - " & Match( Concat( cbNoteContextEdit.SelectedItems, Value & ", " ), "^(?<trim>.*), $" ).trim,
Team: cbNoteTeamEdit.Selected,
Tags: cbNoteContextEdit.SelectedItems,
Country: varCurrentCountry,
Region: varCurrentRegion,
Notes: rteNoteBodyEdit.HtmlText
},
frmNoteAttachmentCPEdit.Updates
);
In the patch you can see first I update the ordinary fields of the list where I have more control in what I put into the list. After this I add the form and tell it to update the attachments with:
frmAttachmentsSharePointList.Uodates
And then it adds the attachments to the correct item in the SharePoint list.
I hope this helps. Let me know if you have more questions.
Ski