I believe such lists would fall under election financing laws and NGOs usually do not do it. Political donations should go to parties and allowing NGOs to interfere in elections would open up a path to influence them. So I presume most everybody has made it illegal.
Other then that you have two groups in the EU parliament which are more to the left. Those are Greens-EFA and GUE/NGL, which are environmentally conscious and left. Greens-EFA is generally pro liberal democracy and pro EU, whereas the GUE/NGL is further to the left often old communist parties and tends to be anti EU. Other then that you have S&D is made up of old social democratic parties, so center left, might be worth it, if you do not have another choice. Renew are a bunch of hardcore neoliberals, EPP are center right conservatives, ID and ECR are fascists. Most parties in the EU, which actually can win elections are in the EU parliament, so for a general overview that is intressting. However individual issues are another thing and can be rather complicated. Great example is Renew the biggest French member is Macrons En Marche, which has some background from the French social democrats and does some actually usefull stuff. They are in constant beef with the German FDP and Dutch VVD both of which are also Renew members and take the most neoliberal position on environmental policy. Also other things matter and when it comes to cutting social welfare En March and FDP VVD show why they are in a political group.