Yes, in multiple ways. Scottish Regiments had been involved in Ireland since the amalgamation of the Scots and English Armies in 1707–14 with the Act of Union bringing about the creation of the British Army.

‘The Troubles’ is something of a broad term but Scottish WWI veterans were active members of the Black and Tans (irregular paramilitary units deployed by the British in an attempt to quell dissent in Ireland in 1916-18). On the other side there were Scots, or Irish-Scots, active within the IRA (Irish Republican Army). Most notably James Connolly, the son of Irish migrants living in Edinburgh. Guns and ammunition also appear to have been clandestinely shipped to Ireland from places like Glasgow, Port Glasgow and Greenock.

Domestically, Scotland has had a long-term issue with sectarianism which arguably can trace its origins to the entrenchment of an exclusionary Presbyterian Church of Scotland during the 1690 constitutional settlement (triggered by William of Orange’s invasion of England in 1688, and the majority of Scottish elites recognising him in 1689; although it did result in a short civil war, 1689-92). Although anti-Catholicism has its roots much earlier in Reformation Scotland and John Knox. However, 1690 saw a real upsurge in official anti-catholic rhetoric. Ultimately, the religious divisions in Scotland, alongside events in Ireland and the migration of Irish Catholic migrant workers in the mid to late 1800s (largely to the West Coast) created increasing tensions.

During The Troubles sectarian football fans (Glasgow Rangers and Celtic) associated themselves with the armed groups operating in Ireland. This last part is more oral history but there are recordings of some collecting money for groups in pubs and, reportedly, sending that money to Ireland to either Protestant Loyalists or Catholic Nationalists.

Check out ‘An Army of Tribes: British Army Cohesion, Deviancy and Murder in Northern Ireland’ by Edward Burke for first-hand British Army accounts, many Scots among them.

For Sectarianism in Scotland see ‘Scotland’s Shame?: Bigotry and Sectarianism in Modern Scotland by Tom Devine