I was raised in the Christian Reformed Church (CRC). If anyone has this whole para-church thing down to a science, it's the CRC. They literally offer cradle-to-grave services to the church body, whether that's Christian education (primary, secondary, and college), retirement facilities and hospice, and mental health - just to name a few. They also have para-church evangelism (U.S./Canada and globally) and poverty relief. There is even a recreational facility that my family used to "attend" for golfing, softball, and other forms of relaxation. You could hardly go through the day without having some involvement with a CRC para-church ministry. To fund all of this infrastructure, churches commit to a "quota" based on the number of members in each church. The quota system was renamed to "ministry shares" (https://www.crcna.org/MinistryShares/ministry-shares-pledge-system) a number of years ago because the perception was that the word "quota" meant a church had to give a fix amount, which was pretty much the case. There is no less of an expectation that a church must contribute its "fair share" with ministry shares, though the stigma of not giving is probably less than what it was before.
I'm not going to tell you that this is a horrible system because of two reasons: (1) I have experienced first-hand the benefits, and (2) because it can work if the right people are running it. The New Testament seems pretty clear that we should care for one another whether that's spiritually or physically (e.g. 1 Cor 12:25-26). Many, many other Christians have cared for me and helped nurture me over the last 59 years. I have much to be grateful for.
What concerns me generally about para-church organizations is what happens when the people with the vision to build the enterprise are no longer in charge. Those who follow them become more distant from the organization's founding principles and lose sight of the mission. For example, the CRC runs a ministry called "World Renew" (https://network.crcna.org/global-mission/world-renew-website) whose mission was to fight poverty on a global scale. It was formerly known as the Christian Reformed World Relief Committee (CRWRC). As CRWRC they did great work. Anyone could pick up a catalog and pick out items from a long list ranging from chickens to water wells and get those items in the hands of a person in need anywhere in the world. My wife and I did this, as did her parents before her. It was easy and effective. Then one day I received an email saying that the CRWRC was changing its name, the logo, and the fonts. They also came up with a tagline - "Living Justice, Loving Mercy". I was asked to vote on the proposal. I pointed out to the ministry that people in need could really care less what typeface the organization used. I also mentioned that nowhere was there any mention of Christ in the proposal. To resolve the second problem they added "Serving Christ" to the end of the new tagline and blamed the design agency for the oversight. The fact that they farmed out this work told me that the people in charge no longer really understood what their mission was. They were just there to figure out how to maximize their dollar intake. So we stopped giving to that particular organization.
In summary, my point here is that para-church organizations can and do do good things for both the church and those outside of it. I would urge caution in supporting any para-church organization. If they can't explain the true purpose of their mission then look for another if you feel led to be a part of a particular activity. Don't assume that because the organization is "Christian" or has good intent that you should support them. We are called to be good stewards of our gifts (1 Peter 4:10). This means time, money, and talent. So please do some legwork before volunteering your time or cash. I would say that any organization, church or para-church, that allows us to focus our thoughts on our unworthiness in salvation is one worth looking into.