It went mostly smoothly despite the overall quality of PS2 homebrew being lower than that of, say, PSP or 3DS. Documentation is... spotty and the tutorials (oh my god, the endless tutorials) are confusing.
The best phat models are 390xx (great except for loud fan) or 500xx (laser said to be less reliable). Slims mostly cannot use HDDs (earliest ones can be modded for HDD, requires soldering).
Open PS2 Loader (OPL) can run PS2 games off an internal HDD, a network share, or a USB drive, in descending order of quality. OPL HDD
is compatible with almost every game at this point, while network introduces slower loads and more compat issues, and the PS2's USB 1.1 is just painfully slow.
Standard PS2 network adapters only support outdated IDE drives so I highly recommend buying a SATA-modded official Sony OEM network adapter, they're available on eBay for $30-40. That way you can use a modern SATA drive of up to 2TB. (
Some hobbyists have also rigged microSD readers to their network adapters, but 2TB microSDs aren't really a thing yet.)
I got a $50
WD Blue (for PS2 choose 5400rpm over 7200, less heat, same performance). Though I have an Matrix Infinity modchip from back in the day, I also got a FreeMcBoot memcard from the seller for $10 extra. This is very handy to have for easy access to homebrew. (Now I kind of wish I didn't have the modchip because it interferes with FMCB, so I have to disable it each boot.)
Beware the cheaper Chinese-clone HDD adapters on eBay that omit the network port. For one, you want the network port. Two, they're waaay less reliable.
Formatted the hard drive in
uLaunchELF (aka wLaunchELF).
Then used a
SATA to USB3 adapter to connect it to my W10 PC whenever I wanted to install ISOs to it.
For PC->HDD installations I found the batch file
HDLBatch was an absolute godsend. I edit the database file that comes with it to make sure all games have correct/optimal titles. If you can get your PC and PS2 talking over Ethernet (I could not) you can also install games over the network, but it'll take ~10x longer. Or if you're doing the network share method just copy the games to the network share (I think, I've not tried this).
Once games are installed you can run them via
Open PS2 Loader and manage certain aspects of them (screenshots, metadata, etc.) via
OPL Manager (Windows app).
Almost every app I listed has, uh, quirks and major learning curves, it's a little brutal (I'm not sure how I'd have installed games without HDLBatch, every purpose-built GUI app I ran into failed me). But everything does work in the end. And then you have a lovely PS2 full of all your favorite classics. Well worth it.
Side note: Because homebrewers haven't been able to gain access to PS2's internal PS1 emulation, OPL relies on outdated, quite lacking software emulation for its nominal PS1 ISO support. I recommend not bothering; play PS1 via disc only (though honestly, I'd rather spare the wear on the PS2 laser).