I see a couple of other comments reccomending exfat; I've had problems with exfat with both the Steam flatpak and the Steam system package. Exfat does not support linux symlinks which are needed for some if not most Steam games to work properly. You will have to re-install your games onto an ext4 or linux-friendly filesystem, for Steam at least.
Emulation and GOG is a different story though. I have both on an exfat drive and I can access and play them with both windows and linux.
In terms of security, you will be at a slight risk using an unsupported os in the future. But hey, some people I know are still on Windows 7, so it isn't a huge risk. As long as you practice basic computer hygene and have an antivirus running (windows defender (easy), malwarebytes (secure), or clamAV (open source) are decent picks) you'll be fine.
If you enjoy Titanfall 2 you might like Call of Duty Black Ops 3. I still havent found a game that handles so well and feels so smooth. It got a lot of flak at the time (2014) because everyone was tired of future shoooters, but imo it has the best fps mechanics not only in cod, but in any fps game. The story is also really good; I wont spoil but it does get kinda philosophical and has plenty of twists and turns.
As others have said, the Half Life series is probably the best fps objectively. I started with 2 and then played 1, so while they do go in order, it isn't required. HL1 is a bit clunky but still great.
Also James Bond 007 games are criminally underrated. Everyone knows about Goldeneye for the N64, but some of my favorites are Nightfire, From Russia with Love, Everything or Nothing, and Goldeneye Reloaded. A lot of the Steam pages were taken down for them though, and are only really playable on console, but definitely worth it if you are able to play