I have used natural sunlight almost to exclusion (though my personal fishroom at present of about 2K gallons plus a few small display tanks have typical/traditional aquarium lights).
The growth and color of corals kept under sunlight is... er, not surprisingly

.... incomparable! What I use and recommend to aquarists/growers is that they find a glazing/lens that admits the most light including max UV as possible. So for skylights, light tubes, atrium glazing, bay windows, greenhouse coverings, etc... this is the goal. Its a bit of a tall order too as most such materials are designed for human habitat/space or terrestrial plants and have/need considerable UV filtering
Still... you can and will find materials with max light and UV admission. These are in fact the least expensive materials (and shortest lifespans... the good and the bad).
Some of your corals will need max UV... some will want little or none at all... and many fall in between. You will need to experiment with shade cloth (dirt cheap from a greenhouse supplier) or the like to determine what is best for your corals. But is is much better and cheaper to filter out free sunlight and free UV than to use a material that blocks some or all of it and you then have to pay (electricity and lamps!) to add it back in.
A mixed garden reef tank with unnatural species selection (corals from very different niches/needs like corallimorphs and shallow water sps corals) will struggle here. Its one of the many reasons why these unnatural reef displays struggle in the long run.
As to the sunlight=algae legend... it is complete bunk, I am happy to say. Nutrients are really THE rate limiting factor for nuisance algae growth. Numerous aquarists can attest to this fact with algae ridden aquaria illuminated by dim or aged bulbs. Healthy tropical reefs under sreaming tropical sun are not havens for nuisance algae either... but when they become damaged and polluted (nutrients), the nuisance algae then gets a foothold until the nutrients can be exported (corals recover and outcompete, source of pollution wanes, etc).
And aquarists with good husbandry will see this too... due care with water changes, vegetable filtration, aggressive skimming, and/or proper feeding/stocking, etc. all lead to healthy systems with little or no nuissance algae. After many years of not scraping 3 or 4 vertical side walls of the glass aquaria in my greenhouse, you still could read a newspaper through the uncleaned side walls.
Rest assured... nutruient levels and water flow are a far greater influence on algae... and an increase in lighting that favors your corals can often also reduce nuisance algae by helping them outcompete the pest.
Food for thought
best regards,
Anthony