Big misunderstanding about Betta and aeration.
You're not aerating the tank for the Betta to breathe, you're aerating the tank to keep the tank aerobic and keep the Betta from suffering infections.
If you change your water each day, the new water is aerated as you put it in.
Also, the more aeration in the tank, the longer Betta can stay down on a single breath and the better rest and play they can get. Betta do also exchange oxygen through their gills, just not a large percentage of their needed intake.
So don't assume that a Betta doesn't need aeration because they take breaths, the aeration is important to the health of their body. More than half the infections bowl Betta get are from the anaerobic nature of stagnant water. Nasty chemicals like hydrogen cyanide can form in thick rock beds in stagnant water.
If you have your Betta in a Walstad style setting, lots of plants in a bowl with good lighting, the plants themselves will snark the carbon dioxide out and the air will naturally solve in from the surface. So plants do aeration.
So for the off-topic question about Guppies. In all categories except aeration, care for guppies is closely the same as Betta. You must aerate either through Walstad environment support of one guppy per gallon or by filtration. Given they're heavy reproducers I go full Walstad and
add a filter with an air stone running heavily in it. (Aquaclear are excelent for this). You'll also want an intake pre-filter sponge on any filtration you use to keep the little guppies from being sucked in.
My advice is to use sponge filters (multiple small ones) for guppy tanks.
You can have guppies, both male and female, with female Betta, but when one drops their young the Betta will hunt them all up. In a large sorority this is generally ok and an easy way to keep the guppy pop down, but in a small sorority or a single Betta in tank this will drive the betta to death by eating.
Female Betta LOVE large fin fancy guppy males, the constant little display they put on has always soothed my sorority.