Hi NCBardeau,
As per your description, I go through your post carefully, yes when we import data (include URL) from Excel to SharePoint online list by default its import text instead of hyperlink in SharePoint online list.
Here I find a solution for you, please follow my below steps.
1.First in Excel file in URL cell/column you need to add” https:// “before in your url address.
- Click on Advanced mode copy the below JSON code and pate into column.
{
"$schema": "https://developer.microsoft.com/json-schemas/sp/v2/column-formatting.schema.json",
"elmType": "a",
"attributes": {
"href": "@currentField",
"target": "_blank"
},
"txtContent": "[$url]"
}