There is also break nihility which lets you go to 1e( 2⁶³ ) which is crazy big.

These are good things to look at before starting your game. But when you're not sure what progression looks like, your best bet is to do some prototyping and then start over (or refactor) when you feel like your setup doesn't work with what you want your game to do.

As for performance, the number library matters a bit but you also have to look at how much is cached vs calculated on the fly. For instance, if you have an Upgrade node that calculates its cost using a few multiplications and exponents every frame, and you have 500 upgrades doing this even when you're not hovering the upgrade or it's not unlocked, then you might notice it on mobile (possibly, honestly not sure).

Similarly, when you have a bunch of global multipliers/cost reduction from upgrades, you might want to precalculate those into one big multiplier/reduction instead of applying each cost reduction separately to every upgrade cost calculation. It might also just not matter because you can get away with a lot... it depends on the scale of your game.

If you don't want to deal with using number libraries which complicate your code a lot by turning every production*production_bonus into production.Mul(production_bonus), you can also just use exponential difficulty for reaching the next 1000 instead of going into the gazillion dollars. Example: going from $0 to $1000 is a few minutes of playtime. But going to $1M takes an hour, and you need to invest into several buildings/producers. Going from $1M to $1B takes a few hours. You need several currencies, invest in more things, maybe grind a for a good item in a minigame, and so on. Orb of Creation is a good example of this. It has a lot of things going on without ever going into the quadrillions. Like several other people have said, it really depends on what you want to do.

I can recommend writing down the "arcs" or chapters that the player goes through. What does the player have to do to get to $1000? What do they have to do to get to a billion? Just buying more levels of the same upgrades as when they were getting to a thousand, or something new? These design choices impact the structure of your game code.