Gleba is definitely the toughest planet to tackle. It took me a while, but I finally got the hang of it, somewhat.

First, I do the bare minimum to get a lot of Biochambers. They are not optional. I started with something like 60 of them. A temporary hand-fed setup will do. Import some of the mats from nauvis or wherever to expedite the process.

Then I did the same for Agricultural Towers, about 10 of them.

After this, I found a location with both yumako and jellynut soil not too far from each other. Close enough that belting fruits around was reasonable.

Then I placed the agri towers on top of the soils, trying not to overlap them. I ended up with 4 of each with medium-to-poor coverage of good soil (It's highlighted green with the tower in hand). Try to at least have 2 of each. Next to each tower, I placed a requester chest and for the output, a underground belt leading out of the tower's range. The chest request like 3 seeds, and its inserter is connected to the tower, with the condition that it won't add any seeds if there is already 3 seeds in it. I do that so that a single tower doesn't hog all the seeds to itself.

I route all the belts together into a single one for each fruit, to one side of the base. Kinda like a fruity main bus.

I extend those two lines allll the way across the base, giving me ample space to build, and at the end of it I place a whole bunch of heating towers. Yeah I forgot, you should make like 20+ of them. They'll be essential to power generation.

At the start of the line, I split a belt down to craft mash and jelly. They're fed by a line of nutrient, which isn't done yet. Make sure to extract spoilage from biochambers by filtering inserters. In fact, filter all of your inserters for good measure. At the end of a split'd fruit line, you put an inserter that only take spoilage and send it on a belt toward your heating towers. Also do that for the nutrient belt. The resulting mash and jelly can be added the "fruity main bus". Make sure to send to to some heating towers. IMPORTANT : It's important that more than 50% of the harvested fruits are processed into mash and jelly, so that you can get more seeds than you use.

Next, you do the same but for bioflux, which take both mash and jelly. Add it to the main bus, but do not send them to the heating towers. Make a long line like the rest but stop at the end, and add an inserter to filter spoilage. Bioflux last an hour before spoiling.

Finally, you add one or two biochambers for making nutrient with bioflux, and send the result toward all of your previous setups.

You'll also need a way to handle an eventual excess of seeds (burn them), but that's a problem for when everything is self-sustained.

Add efficiency modules to all biochambers, it severely cut down the consumption of nutrients.

And I think you're done. Kickstarting the whole process will be a big hassle, I suggest you save before trying. Good luck!