I've seen plenty of references recently where it has been suggested that the 4 nations can take their own approach to travel restrictions. If the Scottish Government want to help St Johnstone, as they have indicated, then it is well within their power to do so. An extract from the BBC published 6 days ago:
"Each UK nation sets its own travel rules.
A Scottish government spokesperson said ministers were "considering the best approach" for arrivals from France "as we look to adopt a four nation approach on international travel, where possible".
Wales said it would be following the change set by England, while Northern Ireland is yet to announce its intention."