FRAME:
Felt Integrated Aero Tri UHC Advanced + TeXtreme carbon fiber, MMC with InsideOut construction, BSA threaded 68mm bottom bracket shell
Your options are going to be Shimano 24mm, SRAM 24/22mm GXP, FSA Mega Exo, BB386EVO (FSA Mega EVO), or SRAM Dub; but NOT BB30 or BBright. You can't fit the bearing and a 30mm spindle into the standard English BB shell.

Just pointing out that MegaExo is the same as Shimano. Just FSA's branding. Per the FSA Website: "MegaExo bottom brackets are available in all thread standards and offer compatibility with Shimano cranks"

This is true but the tolerances are sometimes really, really tight, though moreso in the opposite direction. I mounted a gossamer srm crank with mega exo on a nicer ultegra BB and it took some serious pounding to get it in and some even more serious pounding to remove it.

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Benjamin Deal - Professional - Instagram - TriRig - Lodi Cyclery
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You can: Rotor BSA30 - probably also others around...

Lets clarify a few things as their has been some confusing information posted in response to you.

Firstly you are 100% correct your bike has a BB30. In 2020 Felt moved (back) to threaded BBs but the 2019 IA10 has a standard BB30. This is excellent news as it give you lots of options

Secondly, you are correct that the MegaExo BB you have installed reduces the shell from 30mm to 24mm to accommodate traditional cranks like Shimano.

What has caused confusion is that your bike also has something else pre-installed. An adaptor which is pressed into the BB30 shell which allows you to use a threaded BB in press-fit shell. This is again good news for you because it gives you options.

Overall pretty much any crank available as you will run into very few compatibility issues. Your just need to match the BBs according as follows:

1) With a Shimano or other 24mm spindle crank keep the adaptor in the bike and just use a Shimano English threaded BB (HollowTech in Shimano speak).

2) Use a Rotor or other 30mm BB30 cranks with a BB30 BB. This will require removing the adaptor you currently have in the BB but that's as easy as doing a standard BB30 replacement.

3) Use a Rotor/FSA 30mm crank designed for external BBs with the BB386Evo BB. This final options is the most technically confusing but its basically FSA's answer to your problem. Its also often the cheapest option because FSA is pushing the BB386Evo system by reducing the price of the system.

Overall the good news is that you are aren't going to run into many compatibility issues or super expensive niche components. The language is a bit confusing but start by selecting the cranks you want. Then work backwards as to how you get in into a BB30 shell.

I learned the Shimano/FSA lesson the hard way. Afterwards I had an extra Shimano BB.

This is because at FSA our tolerances tend to be slightly large and Shimano runs slightly undersized. So a FSA or Vision crank will almost always fit tight into a Shimano bottom bracket and opposite a Shimano crank will have slight play in a FSA bottom bracket. This is why we always recommend using a FSA bottom bracket with any FSA or Vision crank. It will help increase the life of the crank and bearings.

Isn't it GREAT when manufacturers make things non-standard so you can't pick the better performing products.
Wonder when a manufacturer is going to start fitting 648.79b wheels and their own sized tyres on new bikes 🤬

Unfortunately different machining processes in manufacturing don't always allow for the end products to come out the same from every brand. We do our best to allow for our products to work with as many other brands as possible but the due to the large amount of standards in the bike industry it doesn't always work out.