I don't think unit linked funds are good value. Their charges are very opaque IMO. Also, there are lock in charges in that they charge you in the event you need need to access the money early (less than 5 years I think).
I went through all of this exact thought process about a year ago. ETF, unit linked funds, UCITS, US domicilied, deemed disposal, DWT, direct share purchase etc etc. Its very overwhelming initially. Investing outside a pension is a pain by my investigation, unless you are buying shares directly, which I didnt want to do.
In the end I got disheartened and gave up. Someone on here suggested that overpaying an SVR mortgage is effectively a ~ 3% guaranteed investment return annually. You'd need to be getting ~ 7% annually on your investment to match this (taking tax into account). This may be something to consider.
Having said that, I dont have a mortgage currently. However, I plan on buying a house at some point in the future and have decided to save any money I had previously intended on investing monthly and use it to buy the house outright instead, thereby saving myself years of interest payments and hopefully almost 100K over the time of the same mortgage term. This is my approach to "investing" in Ireland outside a pension.