There are Linux-native alternatives to Adobe and Affinity suites, though of course if you want to get used to specific app controls and shortcuts for one reason or another, you don’t have much choice.

If you’re OK with using FOSS alternatives, Inkscape and Krita are to Affinity Designer / Adobe Illustrator, GIMP is to Affinity Photo / Adobe Photoshop, Darktable is to Adobe Lightroom and Scribus is to Affinity Publisher / Adobe InDesign. All very capable tools IMO.

Try spelling it backwards ;)

Intel’s Clear Sans.

IBM’s Plex, I’m particularly partial to their condensed sans.

Fira Sans is a good generic recommendation, their mono is again worth considering.

Adobe’s Source family (sans, serif, mono) is another inoffensive, safe choice.

erewhon is a modern workhorse serif that pairs well with all the sans fonts above. It’s derived from Adobe’s Utopia, which is used in quite a few newspapers (clear and legible without taking too much space).

STIX Two was specifically designed to replace Times New Roman in scientific + mathematical publications, if you’re looking for a font that’s different but familiar to Times New Roman, I could not recommend it enough.

Charis SIL was originally designed for laser printers and later modified for use in linguistics, it’s essentially a serif version of Verdana (same designer too). As with all the other fonts mentioned, very broad character set support.

The TeX font catalogue is a treasure trove in general.

Edit: almost forgot, the Libertinus family also comes recommended for a more ‘professional’ look.