Questions about running a modded network

(I use AI for translating this because I'm not a native English speaker, thank you for understanding)

Hi everyone,
I'm seeking some guidance on scaling up my Minecraft server setup. I run a community for a large modpack (400+ mods, Neoforge 1.21.1) that has recently seen a huge surge in popularity called dragoncraft on curseforge. Our player base has grown by a lot and our current servers are constantly full and struggling under the load.

We currently have three servers hosted with BisectHosting (their "Premium" game server plan), each capped at 20 players. It's clear we need to upgrade to accommodate 100+ concurrent players across one or more servers.

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Since I have always used shared gaming servers, i don't know if the performance difference between a shared hosting vs dedicated hosting is that big of a deal I have no benchmark to compare to personally. we are currently trying to hire someone who has sysadmin knowledge but for now it's just me who has to do it. I'm fairly new to backend/network administration, so I'm looking for advice on the best path forward. 

Here’s what I'm thinking and what I need help with, My Current Plan/Questions:
- Is it even possible to have 100 players or 50 players online at the same time in a modded network?
- The pack runs with 10gig max utilization from what I have seen even with 20 people online at the same time, is this normal? Someone said that I should be looking at +1g per player as an estimate is that true? do 100 player servers follow that?
- I have been recommended things like C2ME and Async/ Dimthread is it worth it? Should I be learning more about it or is it of little consequence if I just invest in hardware and get a good Ryzen 9550x
- From what little research I have done, it looks like its better for me to setup 2 x 16g servers with 50 player cap than 1 x 32g server (100 cap) or 5 x 10 g server (20 cap each)
- Currently what I have seen from shared gaming hosting is that after a certain point the entity + player lag brings the tps down or the network has packet issues. Is this something thats 1) normal or is there a problem in the pack/world I need to fix 2) is the tps lag something a better cpu help address. I addressed a lot of the tps lag by making custom spawn balance configs.
- I know I need to move to a dedicated machine, but I'm unsure what specs to target for a heavily modded 1.21.1 server with 100+ players. What CPU (core count/clock speed), RAM, and SSD specs should I be looking for?
- I plan to use Pterodactyl for management. Is this still the standard? Another pack dev recommended I look into [Rampart](https://github.com/Ninjastorm380/rampartfs). Is this relevant for optimizing performance for a large modded server, or are there other tools/software I should consider? Currently I use someaddon's mods for optimization on the server side coupled with lithium, etc.
- I've heard that bare metal storage can get expensive due to the large size of modded world files. Is this a significant cost factor I need to plan for?
- Since I'm coming from Bisect's "Premium" shared game hosting, will a dedicated server provide a tangible performance boost? I'm unsure what hardware their premium plan uses, so it's hard to compare.
- Is a dedicated server the right way to go, or are there more cost-effective or simpler solutions I might be missing (like a very powerful VPS)?

Any advice, resources, or links to guides would be immensely appreciated. Thanks in advance for your help!

(Not looking for specific hosting recommendations because I think that's against the rules but I want to at least know what all i need to be looking for)